1. Preheat oven to 400 degrees.
2. Spray two 8-inch round cake pans with cooking spray.
3. Place 2 Tbsp butter in each of the pans.
4. Place the pans in the oven until the butter has melted.
5. Remove pans from oven.
6. In a medium mixing bowl, beat the flour, 1/4 teaspoons baking powder, sugar, salt, milk and eggs until smooth.
7. Arrange the apple slices into the two pans onto the melted butter.
8. Divide the batter evenly between pans.
9. Spread evenly over the apple slices.
10. Mix the sugar and cinnamon in a small mixing bowl.
11. Sprinkle mixture over the batter in each pan.
12. Bake until puffed and golden brown, about 20-25 minutes.
13. Serve warm with butter and pure maple syrup, if desired.