Preheat your oven to 350°F. Butter a 9×13-inch baking pan generously.

Whisk together the flour, baking powder, cinnamon, nutmeg, and salt in a medium bowl.

Combine melted butter, granulated sugar, and brown sugar in a large bowl. Add eggs and vanilla extract, then beat until smooth.

Mix in the flour mixture and stir until thoroughly combined. Fold in the diced apples.

Transfer the batter to the prepared baking pan and press it into an even layer.

Bake for 30-35 minutes, or until a toothpick inserted in the center comes out clean.

Cool the blondies for at least 15 minutes before slicing.

Drizzle warm caramel sauce over the squares just before serving.