Instructions

1. Brown the butter: Place all 10 Tablespoons of butter in a light-colored saucepan or skillet over medium heat. Cook, stirring frequently, as the butter melts, foams, and begins to sizzle. Continue cooking until it turns golden brown, brown specks appear on the bottom of the pan, and it smells nutty. Remove from the heat and pour the browned butter into a heat-safe mixing bowl so it doesn’t continue cooking in the hot pan. Scrape in all of the browned bits from the bottom of the skillet.
2. Measure out and reserve 1 1/2 Tablespoons of the browned butter for the glaze. Set the reserved butter aside and let the remaining browned butter cool slightly for the blondie batter.
3. Preheat the oven to 350°F (175°C). Lightly grease an 8-inch square baking pan, line it with parchment paper, leaving an overhang on the sides, and lightly grease the parchment.
4. Cook the apples: Return the same skillet to the stove (there’s no need to wash it). Add the diced apples, lemon juice, brown sugar, cinnamon, and nutmeg. Cook over medium heat for about 3-5 minutes, stirring occasionally, until the apples begin to soften but still hold their shape. Remove from the heat and set aside to cool slightly.
5. In a separate bowl, whisk together the flour, baking powder, salt, cinnamon, and nutmeg.
6. Add the brown sugar to the slightly cooled browned butter and whisk until combined. Add the egg and vanilla and whisk until smooth.
7. Add the dry ingredients and stir just until combined. The batter will be thick.
8. Fold in the cooked apples until evenly distributed.
9. Spread the batter evenly into the prepared pan and smooth the top.
10. Bake for about 25–30 minutes, or until the top is set and a toothpick inserted near the center comes out with a few moist crumbs. Do not overbake.
11. Let the blondies cool completely in the pan. Using the parchment paper overhang, lift them out of the pan before glazing.
12. Make the brown butter glaze: If the reserved browned butter has solidified, warm it briefly until just melted. Whisk it together with the powdered sugar, vanilla, and 1 Tablespoon of milk. Add more milk, a little at a time, until the glaze reaches your desired consistency. If it becomes too thin, add a little more powdered sugar.
13. Drizzle or spread the glaze over the completely cooled blondies. Let the glaze set before slicing and serving.
14. Store the blondies in an airtight container at room temperature for up to 2 days, or in the refrigerator for up to 5 days.