Instructions

• Preheat oven to 350°F (177°C). Spray a small cast-iron skillet or a 4–6" cake pan with nonstick cooking spray.
• In a medium bowl, stir together the melted unsalted butter (2 tbsp) and packed brown sugar (1/4 cup) until combined.
• Add the large egg yolk and stir or whisk until smooth and well combined.
• Stir in the vanilla extract (1/2 tsp), baking powder (1/4 tsp), and salt (1/8 tsp) until evenly distributed.
• Add the all-purpose flour (1/3 cup) and stir just until the flour is incorporated and no large streaks remain; do not overmix.
• Fold in the 1/2 cup of mix-ins until evenly distributed through the batter.
• Spoon the batter into the prepared skillet or pan and smooth the top with a spatula.
• Bake for 18–24 minutes, checking at 18 minutes. The blondie is done when the outer edges and top are golden and set but the center is still slightly jiggly — err on the side of underbaking for a gooey center.
• Remove from the oven and let cool in the pan for about 10–15 minutes (it will continue to set as it cools). Serve warm, optionally with ice cream and caramel sauce.