1 1/2 cups peeled and diced apples (about 2 medium apples)
Instructions
Place the butter in a medium saucepan over medium heat. Melt the butter, then continue cooking it while stirring constantly. The butter will foam up and then develop small brown bits at the bottom. Once it smells nutty and looks amber in color, remove it from the heat immediately and pour it into a large mixing bowl to cool slightly.
Preheat your oven to 350°F (175°C). Line an 8×8 inch square baking pan with parchment paper, leaving an overhang on the sides for easy removal. Peel, core, and dice your apples into small, uniform half-inch pieces so they cook evenly throughout the blondies.
To the bowl of slightly cooled brown butter, add the brown sugar and granulated sugar. Whisk until well combined. Add the egg and vanilla extract, beating vigorously until the mixture looks smooth and glossy. This helps create that signature crackly blondie top.
In a separate small bowl, whisk together the flour, cinnamon, nutmeg, baking powder, and salt. Gently fold the dry ingredients into the butter mixture using a spatula. Mix only until a few streaks of flour remain to avoid overworking the gluten.
Fold the diced apples into the thick batter until evenly distributed. Spread the batter into your prepared baking pan, smoothing the top with a spatula. Bake for 30 to 35 minutes, or until the edges are golden and a toothpick inserted into the center comes out with just a few moist crumbs.
Allow the blondies to cool completely in the pan. This is crucial for the structure, as they will continue to set as they cool. Once cool, use the parchment paper to lift the block out of the pan and slice into 16 even squares.