Jam Bars with Oat Crumble Topping

These jam bars are a pantry-friendly, reliably tasty tray bake that I come back to when I want something homey without fuss. Shortbread-like base, a generous layer of jam, and a crunchy oat crumble on top—simple elements that combine into a snackable, tea-time staple. They travel well, keep their shape, and slice neatly once chilled.

I like to think of them as a crowd-pleaser you can make from ingredients you probably already have. The method is straightforward: a buttery shortbread base, a swift jam layer, then an oat-forward crumble that bakes to light gold. No rolling pin, no laminating, and no need to worry about precision beyond measuring.

Read through the ingredients and the single, ordered set of steps before you begin. Little details—chilled butter, a hot crust before the jam goes on, and cooling completely—make the difference between crumbly chaos and clean bars. If you want variations, I’ll list swaps and troubleshooting tips further down.

What You’ll Need

Ingredients

• 2 cups all purpose flour — for the shortbread base; provides structure and a tender crumb.
• ⅓ cup granulated sugar — sweetens the shortbread base without making it cakey.
• ¼ teaspoon kosher salt — balances sweetness and highlights butter flavor in the base.
• ½ teaspoon baking powder — a small lift so the base isn’t too dense.
• ¾ cup unsalted butter (1-1/2 sticks), chilled and cut into small pieces — cold butter creates the sandy shortbread texture when cut into the flour.
• 3 tablespoons milk — moistens the dough so it can be pressed into the pan; use the exact amount called for.
• 1 teaspoon almond extract — adds a bright, nutty note; a little goes a long way.
• 1-1/2 cups quality jam or fruit preserves — the star flavor; choose a thick, good-quality jam for best results.
• 1-1/2 cups all purpose flour — for the oat crumble topping; gives body and tenderness.
• ½ cup light brown sugar, lightly-packed — adds moisture and caramel notes to the crumble.
• ¼ cup granulated sugar — balances the brown sugar and helps with browning.
• ½ teaspoon kosher salt — enhances sweetness and overall flavor in the topping.
• ½ teaspoon baking powder — lightens the crumble slightly so it isn’t too compact.
• ½ teaspoon ground cinnamon — warm spice that complements fruit jams.
• ⅛ teaspoon ground cardamom (optional) — a subtle floral note; include only if you like the flavor.
• ½ cup rolled oats (not quick-cooking) — gives the topping chew and visible oat texture.
• ¾ cup unsalted butter (1-1/2 sticks), chilled and cut into small pieces — creates clumps in the crumble that bake to golden crunch.
• Powdered sugar for dusting (optional) — a finishing touch for presentation; entirely optional.

Jam Bars with Oat Crumble Topping: How It’s Done

1. Preheat oven to 375°F (190°C). Position a rack in the middle of the oven. Line a 13x9x2-inch baking pan with parchment paper leaving about a 2-inch overhang on the long sides; lightly coat the parchment with cooking spray.
2. Make the shortbread base: in a large bowl whisk together 2 cups all purpose flour, 1/3 cup granulated sugar, 1/4 teaspoon kosher salt, and 1/2 teaspoon baking powder.
3. Add 3/4 cup chilled unsalted butter (cut into small pieces) to the flour mixture. Use a pastry blender, two knives, or a fork to cut the butter into the dry ingredients until the mixture looks sandy and forms fine crumbs.
4. In a small measuring cup stir together 3 tablespoons milk and 1 teaspoon almond extract. Pour this liquid over the crumb mixture and stir just until moistened throughout; the dough will remain crumbly. Do not overwork.
5. Transfer the crumbly dough to the prepared pan. Press it evenly and firmly into the bottom of the pan to form an even layer.
6. Bake the crust for 12–15 minutes, until the center is just set and the edges are beginning to turn light brown. Remove the pan from the oven and leave the oven on.
7. While the crust is baking, make the oat crumble topping: in a medium bowl whisk together 1 1/2 cups all purpose flour, 1/2 cup light brown sugar (lightly packed), 1/4 cup granulated sugar, 1/2 teaspoon kosher salt, 1/2 teaspoon baking powder, 1/2 teaspoon ground cinnamon, and 1/8 teaspoon ground cardamom (optional). Stir in 1/2 cup rolled oats.
8. Add 3/4 cup chilled unsalted butter (cut into small pieces) to the topping mixture. Cut the butter into the dry ingredients with a pastry blender, two knives, or a fork until the mixture is crumbly and holds together in small clumps.
9. Spread 1 1/2 cups jam or fruit preserves in an even layer over the hot crust. Use a spatula or the back of a spoon to smooth it, taking care not to press through the crust.
10. Sprinkle the prepared crumble topping evenly over the jam layer so the jam is fully covered.
11. Return the pan to the oven and bake 25–30 minutes, until the crumble topping is light golden brown.
12. Remove the bars from the oven and let them cool completely in the pan on a wire rack (cooling completely will help them set and make slicing cleaner).
13. Use the parchment overhang to lift the bars from the pan. If desired, dust with powdered sugar, then slice into bars and serve.

Why It Works Every Time

• Layering and timing. Baking the crust before adding the jam prevents sogginess. A hot, set crust seals slightly and gives the jam something firm to sit on.
• Cold butter for texture. Chilled butter cut into flour creates those sandy crumbs in the base and clumps in the topping that yield flaky, melt-in-your-mouth bits after baking.
• Simple chemistry. The combination of a little baking powder and cold butter in both layers keeps the base tender but structured and the topping light rather than dense.
• Oats for structure and chew. Rolled oats hold their texture in the oven and provide contrast to the smooth jam layer.

If You’re Out Of…

• Jam or fruit preserves — Use any jam you have on hand. For a thicker spread, choose preserves or conserve so the filling won’t run during cutting.
• Almond extract — Omit it. The bars will still taste buttery and bright from the jam; omit rather than substituting strong extracts unless you prefer another flavor.
• Light brown sugar — Replace with dark brown sugar for a deeper molasses note, or use equal granulated sugar if that’s all you have (the flavor will be slightly different).
• Rolled oats — If you only have quick oats, they’ll work in a pinch but the topping will be less textured and may compact more in baking.
• Chilled butter — You can briefly chill the cut butter pieces in the freezer before cutting them into the dry ingredients; the goal is small, cold fat pieces.

Equipment at a Glance

• 13x9x2-inch baking pan — the specified size keeps bake time and layer proportions accurate.
• Parchment paper — makes lifting and slicing much easier.
• Pastry blender, two knives, or fork — for cutting chilled butter into flour for both layers.
• Mixing bowls — large and medium for base and topping.
• Spatula or back of a spoon — to spread jam over the hot crust.
• Wire rack — for cooling completely so the bars set properly.

Learn from These Mistakes

• Pressing the jam into the crust. If you push the jam into the shortbread, you’ll end up with an uneven layer and a soggy base. Smooth gently on top only.
• Using warm butter. If your butter is not chilled, the base and crumble will be greasy and won’t form the desirable clumps and crumbs.
• Cutting too early. Slicing before cooling yields ragged edges and spreading jam. Cool completely in the pan first.
• Overworking the dough. Stirring the base until smooth will develop gluten and make the crust tough—leave it crumbly and press gently.

How to Make It Lighter

• Reduce butter carefully. You can try trimming 1–2 tablespoons of butter from each 3/4-cup measure, but the texture will be less rich and clump formation in the crumble will be reduced.
• Use lower-fat milk. Swap in a lower-fat milk for the 3 tablespoons called for; it won’t hurt the texture but won’t hugely lighten calories.
• Choose fruit-forward jam. Using a jam with more fruit and less sugar (or a lighter fruit spread) reduces overall sugar content, though the bars are still a sweet treat.

Behind-the-Scenes Notes

I test these bars across different jams and ovens. Jam consistency matters: very runny store jams sometimes seep; thick preserves or seedless raspberry conserve work best. The double appearance of all-purpose flour in the ingredients is deliberate—one portion for the shortbread base, one for the crumble topping. The repeat of chilled butter is similarly intentional: the recipe uses a total of 1-1/2 sticks for the base and another 1-1/2 sticks for the topping, cut cold for texture.

The optional cardamom is a subtle accent that plays well with stone-fruit preserves and apricot jam. If you like spice blends, a pinch more cinnamon is always friendly. The goal is balance: buttery base, bright jam, and slightly crunchy oat topping.

Meal Prep & Storage Notes

• Cooling and slicing. Cool completely before slicing for neat bars. Re-chill briefly if the jam seems very soft before cutting.
• Room temperature storage. Store bars in an airtight container at room temperature for up to 3 days.
• Refrigeration. For longer keeping, refrigerate up to 7 days; bring closer to room temperature before serving for best texture.
• Freezing. Freeze whole or cut bars layered between parchment for up to 3 months. Thaw in the refrigerator or at room temperature before serving; powdered sugar can be added after thawing.

Common Questions

• Can I use homemade jam? Yes. Thicker homemade preserves are ideal. If your jam is very runny, simmer it briefly to reduce excess liquid before using.
• Do I have to use almond extract? No. It’s included for a bright note. You can omit it or use a small splash of vanilla if you prefer, though the recipe calls specifically for almond extract.
• How do I get clean slices? Cool completely and use a sharp knife. Wiping the knife between cuts helps if jam clings to the blade.
• Can I halve the recipe? Yes, but adjust pan size and bake times accordingly; a smaller pan will require slightly less baking time for both crust and final bake.

In Closing

Jam Bars with Oat Crumble Topping are one of those dependable treats I make when I want something comforting without drama. They showcase pantry staples and a favorite jam, bake up predictably, and reward patience at the cooling stage with tidy, portable bars. Keep the butter cold, the crust hot when you spread the jam, and the bars cool before slicing—and you’ll get consistently great results.

These are perfect for afternoon tea, school lunches, or a simple dessert. Experiment with jams and enjoy how a small change in filling transforms the whole batch. If you try them, I’d love to hear which jam you chose and how the crumble turned out.

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Jam Bars with Oat Crumble Topping

Shortbread-style crust topped with jam and a crunchy oat crumble, baked until golden and optionally dusted with powdered sugar.

Prep Time15 minutes mins

Cook Time45 minutes mins

Total Time1 hour hr

Servings: 16 servings

Ingredients

Ingredients

• 2 cupsall purpose flour
• 1/3 cupgranulated sugar
• 1/4 teaspoonkosher salt
• 1/2 teaspoonbaking powder
• 3/4 cupunsalted butter 1-1/2 sticks chilled and cut into small pieces
• 3 tablespoonsmilk
• 1 teaspoonalmond extract
• 1-1/2 cupsquality jam or fruit preserves
• 1-1/2 cupsall purpose flour
• 1/2 cuplight brown sugar lightly-packed
• 1/4 cupgranulated sugar
• 1/2 teaspoonkosher salt
• 1/2 teaspoonbaking powder
• 1/2 teaspoonground cinnamon
• 1/8 teaspoonground cardamom optional*
• 1/2 cuprolled oats not quick-cooking
• 3/4 cupunsalted butter 1-1/2 sticks, chilled and cut into small pieces
• powdered sugar for dusting optional

Instructions

Instructions

• Preheat oven to 375°F (190°C). Position a rack in the middle of the oven. Line a 13x9x2-inch baking pan with parchment paper leaving about a 2-inch overhang on the long sides; lightly coat the parchment with cooking spray.
• Make the shortbread base: in a large bowl whisk together 2 cups all purpose flour, 1/3 cup granulated sugar, 1/4 teaspoon kosher salt, and 1/2 teaspoon baking powder.
• Add 3/4 cup chilled unsalted butter (cut into small pieces) to the flour mixture. Use a pastry blender, two knives, or a fork to cut the butter into the dry ingredients until the mixture looks sandy and forms fine crumbs.
• In a small measuring cup stir together 3 tablespoons milk and 1 teaspoon almond extract. Pour this liquid over the crumb mixture and stir just until moistened throughout; the dough will remain crumbly. Do not overwork.
• Transfer the crumbly dough to the prepared pan. Press it evenly and firmly into the bottom of the pan to form an even layer.
• Bake the crust for 12–15 minutes, until the center is just set and the edges are beginning to turn light brown. Remove the pan from the oven and leave the oven on.
• While the crust is baking, make the oat crumble topping: in a medium bowl whisk together 1 1/2 cups all purpose flour, 1/2 cup light brown sugar (lightly packed), 1/4 cup granulated sugar, 1/2 teaspoon kosher salt, 1/2 teaspoon baking powder, 1/2 teaspoon ground cinnamon, and 1/8 teaspoon ground cardamom (optional). Stir in 1/2 cup rolled oats.
• Add 3/4 cup chilled unsalted butter (cut into small pieces) to the topping mixture. Cut the butter into the dry ingredients with a pastry blender, two knives, or a fork until the mixture is crumbly and holds together in small clumps.
• Spread 1 1/2 cups jam or fruit preserves in an even layer over the hot crust. Use a spatula or the back of a spoon to smooth it, taking care not to press through the crust.
• Sprinkle the prepared crumble topping evenly over the jam layer so the jam is fully covered.
• Return the pan to the oven and bake 25–30 minutes, until the crumble topping is light golden brown.
• Remove the bars from the oven and let them cool completely in the pan on a wire rack (cooling completely will help them set and make slicing cleaner).
• Use the parchment overhang to lift the bars from the pan. If desired, dust with powdered sugar, then slice into bars and serve.

Equipment

• 13x9x2-inch baking pan
• Parchment Paper
• Cooking spray
• pastry blender (or two knives or fork)
• Oven
• Wire Rack
• Spatula
• Measuring cups and spoons

Notes

Notes
*The brand of ground cardamom I use is very fragrant, so 1/8 teaspoon gives the crumble topping a nice, but not overly-assertive hint of the spice. If your cardamom isn’t as aromatic, or if you prefer a stronger flavor, increase to 1/4 teaspoon.
**You can also use a food processor to cut the butter into the flour-sugar mixture. For a tender crust and streusel, use short pulses and be careful not to overprocess. When using a food processor, I prefer to incorporate the liquid ingredients in the base and the oats in the crumble topping by hand.