Preheat oven to 350 degrees F (175 degrees C). Lightly grease a 9x13-inch baking dish.
Beat butter, white sugar, brown sugar, and eggs together in a bowl using an electric mixer until smooth and creamy. Beat flour into creamed butter mixture until well combined; add baking powder and beat. Stir cinnamon into batter. Fold apples into batter; spread into the prepared baking dish.
Bake in the preheated oven until a toothpick inserted in the center comes out with moist crumbs, about 45 minutes.
