Preheat oven to 350°F and grease 8 or 9-inch springform pan.
Cream butter and 1 cup granulated white sugar together until a smooth texture is reached.
While blending, add in eggs one at a time. Add flour and baking powder. Mix until smooth and uniform.
Spread cake batter in greased pan. The batter will be sticky so be careful.
Peel and slice apples and place on top of cake batter. Overlapping apples and pressing down into the cake just slightly. The cake batter will rise around the apples.
Sprinkle the extra 3 tbsp. granulated sugar on top of the batter, but don't mix in. This step is optional.
Bake cake for 40-45 minutes or until a toothpick comes out clean.
Remove baked cake promptly from pan and let completely cool before cutting into it. Dust with powdered sugar on top and enjoy.