Preparation

• Brown the butter for the blondies and the icing: Place all 20 Tablespoons of butter in a light-colored skillet over medium heat. Stir or whisk the butter constantly as it melts, until it begins to foam. After 5–8 minutes, the butter will begin browning with a nutty aroma. Remove from heat and pour into a heat-safe glass bowl, reserving 3 tablespoon for icing.
• Prepare the apples by adding them, maple syrup/brown sugar, and cinnamon to the pan, cooking until softened, about 3–5 minutes.
• Preheat oven to 350°F (177°C). Line a 9×13-inch baking pan with parchment paper, leaving an overhang.
• Make the blondies: In a large bowl, whisk together flour, baking powder, salt, cinnamon, and nutmeg.
• In a medium bowl, whisk together the brown butter, brown sugar, eggs, and vanilla extract. Combine wet and dry ingredients, folding in the apples.
• Spread batter in the prepared pan and bake for about 35 minutes, until the top is lightly browned and a toothpick comes out mostly clean. Cool completely.
• Make the icing: If the reserved brown butter has solidified, warm it, then whisk with confectioners’ sugar, milk, vanilla extract, and salt. Adjust thickness as needed.
• Lift the blondies out of the pan using the parchment, transfer to a cutting board, and cut into squares. Store covered at room temperature for up to 2 days or in the refrigerator for up to 1 week.