Apple Cake Tatin

Some friends came to dinner tonight and we had Lemon Chicken Pasta, Baby Blue Salad, and this terrific apple cake. The recipe was inspired by one from Ina Garten, but I've streamlined it a bit. This upside-down cake is great as a dessert (served with vanilla ice cream, of course) or for breakfast.

Apple Cake Tatin
2 Granny Smith apples
Vegetable cooking spray
1 cup brown sugar
1/2 cup butter, softened
3/4 cup granulated sugar
2 eggs
1 tsp. vanilla
1/3 cup sour cream
1 1/4 cups all-purpose flour
1/2 tsp. baking powder
1/4 tsp. salt

1. Peel apples; cut in half. Use a melon baller to core apples. Cut apples halves into slices. Spray a 9-inch pie plate with cooking spray; place apple slices in an even layer in bottom of pie plate. Sprinkle evenly with 1 cup brown sugar.
2. Beat butter and granulated sugar with an electric mixer until creamy. Add eggs, 1 at a time, beating until blended after each addition. Beat in vanilla and sour cream.
3. Combine flour and next 2 ingredients. Gradually add flour mixture to butter mixture, beating until blended. Pour batter over apple mixture in pie plate.
4. Bake at 350° for 40 minutes. Cool 5 minutes. Invert onto a serving plate.