Preheat oven to 350°F. Line a 9×13-inch baking pan with parchment paper, leaving some overhang for easy removal.

In a large bowl, whisk together the melted butter, brown sugar, and granulated sugar until smooth. Add the eggs and vanilla extract and whisk until well combined.

In a separate bowl, whisk together the flour, baking powder, cinnamon, nutmeg, and salt. Gradually add the dry ingredients to the wet ingredients, stirring just until combined.

Fold in the diced apples until evenly distributed throughout the batter.

Spread the batter evenly into the prepared baking pan. Bake for 25–30 minutes, or until the edges are lightly golden and a toothpick inserted into the center comes out with a few moist crumbs.

Let the blondies cool completely in the pan before slicing into squares.

Enjoy!