I make these Peanut Butter Krispie Brownies whenever I need a guaranteed crowd-pleaser. They start with a simple cake-like brownie base and finish with a marshmallow layer topped in a warm, glossy peanut butter–chocolate mixture that binds crunchy Rice Krispies. The result is dense, chewy brownies beneath a playful, crackling cereal topping — a textural love story that always disappears fast.
There’s nothing fancy here, just a method that treats packaged components with care so every layer behaves. You bake the brownies, cool them completely, sandwich on marshmallow creme, then press on the warm cereal–peanut butter–chocolate topping. Chill, slice, and serve. Practical. Repeatable. Delicious.
Below you’ll find the exact ingredient list, the step-by-step method from start to finish, storage tips, a few smart swaps, and the small mistakes I’ve learned to avoid. If you want a dessert that travels well, stores reliably, and makes plenty, this is one to keep bookmarked.
What’s in the Bowl
Ingredients
- 1(18-oz)package brownie mix, plus ingredients to make cake like brownies — The boxed mix keeps this fast; follow the package for a cake-like texture that supports the toppings.
- 1(7-oz)jar marshmallow creme — Provides a sticky, spreadable middle layer that seals crumbs and gives a smooth surface for the cereal topping.
- 1cupcreamy peanut butter — Use creamy for a smooth, spreadable glaze that melds with the chocolate; it also helps the cereal bind together.
- 1(12-oz)package semi-sweet chocolate chips — Melts into a shiny coat with the peanut butter; semi-sweet balances the sugar of the marshmallow and brownies.
- 4cupsRice Krispie cereal — Gives crunch and lightness to the top layer; measure after gently pouring into the cup to avoid crushing.
How to Prepare Peanut Butter Krispie Brownies
- Line a 9×13-inch pan with parchment paper, leaving a few inches of overhang on two opposite sides for lifting the baked brownies out later.
- Prepare the brownie batter according to the package directions for cake-like brownies. Pour the batter into the prepared pan and bake according to package directions.
- Remove brownies from the oven and let them cool completely in the pan before proceeding.
- When brownies are completely cool, spread the entire 7-oz jar of marshmallow creme evenly over the top.
- In a medium saucepan set over low heat, combine the 1 cup creamy peanut butter and the 12-oz package of semi-sweet chocolate chips. Stir continuously until the mixture is fully melted and smooth.
- Remove the pan from the heat and gently fold in the 4 cups Rice Krispie cereal until the cereal is evenly coated.
- Immediately spread the peanut butter–chocolate–Rice Krispie mixture evenly over the marshmallow layer, using a spatula and pressing gently so the cereal layer adheres without tearing the marshmallow.
- Cover the pan and chill until the top layer is set and firm, about 1 hour.
- Use the parchment overhang to lift the slab from the pan, then cut into squares.
Why Cooks Rave About It
This recipe hits a handful of flavor and texture checkpoints that cooks love. First, the brownie base delivers familiar, fudgy satisfaction without fuss. The marshmallow creme creates a neutral, adhesive middle that keeps the cereal layer from bleeding into the brownie — it acts like an edible glue. Finally, the warm peanut butter–chocolate mixture envelopes the cereal, giving both shine and chew while the Rice Krispies provide a light snap that contrasts the dense brownie.
It’s reliable. Using processed components (brownie mix, marshmallow creme, cereal) means consistent results every time, and the assembly is forgiving: if the cereal layer is slightly uneven you’ll still get great flavor and texture. It’s also crowd-friendly — people love the nostalgia factor and the hand-friendly squares are easy to serve at parties.
Quick Replacement Ideas
- Swap semi-sweet chocolate chips for milk chocolate chips if you prefer a sweeter top.
- Use crunchy peanut butter if you want extra texture in the topping, though the cereal already provides crunch.
- If you don’t have Rice Krispies, crisped rice cereal with similar crunch will work.
Gear Up: What to Grab
- 9×13-inch baking pan — Sized to match the recipe and to produce a slab you can cut into bars.
- Parchment paper — Essential for the lift-out trick so you don’t cut in the pan.
- Medium saucepan — For melting peanut butter and chocolate gently.
- Spatula and wooden spoon — A silicone spatula is ideal for spreading and pressing the cereal layer.
- Measuring cups — Especially for accurately measuring the 4 cups of cereal.
Easy-to-Miss Gotchas
These are small things that can make or break the top layer:
- If the brownies aren’t completely cool before the marshmallow goes on, the marshmallow will melt and thin out — cool patience matters.
- Keep heat low when melting peanut butter and chocolate. High heat scorches chocolate and changes texture.
- Fold the cereal in gently but quickly. If it sits too long, the mixture can seize or lose gloss before you spread it.
- Press the cereal layer gently. Pressing too hard will tear the marshmallow layer; too light and pieces won’t adhere well.
- Don’t rush the chill. The top needs about an hour to firm up; slicing while warm will make messy squares.
Smart Substitutions
Substitutions can keep this flexible without losing the spirit of the bar. A few notes:
- For peanut allergies: Replace peanut butter with sunflower seed butter. The melting behavior is similar, but color and flavor will change slightly.
- For a darker chocolate punch: Swap semi-sweet for bittersweet chocolate chips — expect a less sweet finish and a more intense chocolate note.
- To reduce sweetness slightly: Choose a brownie mix labeled “less sweet” or one with a darker chocolate profile; it balances the marshmallow and cereal.
Chef’s Rationale
I treat each component to play a specific role. The boxed brownie mix handles the base because it’s dependable and quick; this recipe is about layers, not scratch baking. The marshmallow creme is not there for flavor alone — it prevents the sticky cereal topping from sinking into the brownie and provides a smooth plane for spreading. The peanut butter with chocolate creates a glue that sets shiny and holds the cereal intact. Each choice is about functional harmony: stability, texture contrast, and easy assembly.
When I test variations, I always keep those roles in mind. If the marshmallow is swapped for a ganache, for example, the cereal will sink or slip. If you preserve the functional role (a spreadable, adhesive middle), you can experiment; otherwise you lose the structure that makes these bars slice cleanly and store well.
Best Ways to Store
These bars store well because of the marshmallow layer and the firm top. Here’s how I handle leftovers:
- Room temperature: Store in an airtight container for up to 2 days. Keep layers flat to prevent the cereal topping from breaking.
- Refrigerator: For up to 5 days in an airtight container. Chilling keeps the top firm, and it actually slices cleaner when cold.
- Freezer: Wrap individual squares in plastic wrap and store in a sealed container for up to 2 months. Thaw in the fridge before serving to prevent sogginess.
Quick Q&A
- Can I make these ahead? Yes. Make them up to 2 days ahead and keep chilled, or freeze squares individually for longer storage.
- Can I use homemade brownies? You can, but match the cake-like texture the box calls for. Very fudgy, gooey brownies may not support the layers as well.
- What if the top won’t set? Ensure you melted the peanut butter and chocolate fully and that you chilled the pan for at least an hour. If ambient temperature is warm, place the pan in the refrigerator uncovered for faster setting.
- How do I get clean cuts? Use a sharp knife and chill first. Wiping the knife between cuts helps if the top is sticky.
Save & Share
If this sounds like your kind of dessert, save the page and give it a try on your next gathering. It’s simple to assemble, travels well, and makes plenty for a crowd. If you share photos, tag where you found the recipe and note any swaps you tried — I love seeing other people’s tweaks. And if you need a version adapted for allergies or a party-sized pan change, ask — I’ll walk you through it.
Peanut Butter Krispie Brownies
Ingredients
Ingredients
- 1 18-ozpackage brownie mix, ,plus ingredients to make cake like brownies
- 1 7-ozjar marshmallow creme
- 1 cupcreamy peanut butter
- 1 12-ozpackage semi-sweet chocolate chips
- 4 cupsRice Krispie cereal
Instructions
Instructions
- Line a 9×13-inch pan with parchment paper, leaving a few inches of overhang on two opposite sides for lifting the baked brownies out later.
- Prepare the brownie batter according to the package directions for cake-like brownies. Pour the batter into the prepared pan and bake according to package directions.
- Remove brownies from the oven and let them cool completely in the pan before proceeding.
- When brownies are completely cool, spread the entire 7-oz jar of marshmallow creme evenly over the top.
- In a medium saucepan set over low heat, combine the 1 cup creamy peanut butter and the 12-oz package of semi-sweet chocolate chips. Stir continuously until the mixture is fully melted and smooth.
- Remove the pan from the heat and gently fold in the 4 cups Rice Krispie cereal until the cereal is evenly coated.
- Immediately spread the peanut butter–chocolate–Rice Krispie mixture evenly over the marshmallow layer, using a spatula and pressing gently so the cereal layer adheres without tearing the marshmallow.
- Cover the pan and chill until the top layer is set and firm, about 1 hour.
- Use the parchment overhang to lift the slab from the pan, then cut into squares.
Equipment
- 9×13-inch Cake Pan
- Parchment Paper
Notes
Here is our favorite recipe for homemade brownies:https://www.plainchicken.com/bisquick-brownies/
You will need to double our homemade recipe and bake in a 9×13-inch pan.
I leave out the walnuts or pecans when I use this homemade brownie recipe in this dessert.
I use Jif smooth peanut butter. You can use any brand of peanut butter that you enjoy. Smooth or crunchy works just fine.
I used semi-sweet chocolate chips. Milk chocolate or dark chocolate chips would also work great.
I melted the peanut butter and chocolate on the stovetop, but you can also melt them in the microwave.
How do I know if my brownies are done? Bake the brownies until a toothpick inserted into the center of the brownies comes out clean or with only crumbs, no batter on it.
My biggest tip for making these brownies is to line your pan with parchment paper or aluminum foil before baking the brownies.You want the parchment paper to hang over the edges a bit. This will help you when you go to get the brownies out of the pan. I run a knife around the sides of the pan before lifting them out of the pan.
You want the parchment paper to hang over the edges a bit. This will help you when you go to get the brownies out of the pan. I run a knife around the sides of the pan before lifting them out of the pan.
You can cut the recipe in half and make the recipe in an 8-inch or 9-inch square pan.
How to store brownies? Store the brownies in an airtight container on the countertop.
How long do brownies keep? The brownies will keep for 3 to 4 days in an air-tight container.
