Preheat your oven to 350 degrees F. Line an 8 x 8 inch baking pan with parchment paper.
Cream the butter and sugars together in a large bowl until light and fluffy. Add egg and vanilla extract, mixing until smooth.
Whisk together the flour, baking powder, salt, cinnamon, and nutmeg in a separate bowl.
Add dry ingredients to wet ingredients and stir just until combined. Gently fold in diced apples.
Spread the batter evenly into your prepared pan.
In a small bowl, mix the cinnamon and sugar topping. Sprinkle it evenly over the top of the batter.
Bake for 25-30 minutes, or until the top is set and a toothpick comes mostly clear (a few moist crumbles are fine).
Let cool before slicing.
