Apple Upside-Down Cake

So I was originally going to make this for my friend's birthday but due to the fact that it takes me forever to peel apples, I didn't have enough time.  I made this while at my parents' place on Sunday for Sunday dinner, only this was the dessert.  It was delicious and I'm so glad I got to use more of the apples I picked from the orchard.  It was from my Cooking Light Way to Bake cookbook.  I added some Apple Spice for an extra flavor, you don't have to or you could just use cinnamon. 

Here's what you'll need:

for the topping (or rather bottom of the pan):
Cooking spray
3/4 cup sugar
1/4 cup water
3 cups (1/4" thick) slices peeled Rome apples (I used whatever apples I had, but the book says 2 large ones should equal 3 cups)
1/4 cup chopped walnuts
1/4 teaspoon Penzeys Apple Spice (optional)

Cake:
5.3 ounces cake flour (about 1 1/3 cups)
1 1/2 teaspoons baking powder
1/4 teaspoon salt
2/3 cup sugar
3 tablespoons butter, softened
2 large egg yolks
1 teaspoon vanilla extract
1/2 cup 1% low-fat milk
3 large egg whites

First preheat the oven to 350 degrees.  Coat a 9" round cake pan with cooking spray.
To prepare topping, combine 3/4 cup sugar and 1/4 cup water in a small heavy saucepan over medium-high heat; cook until sugar dissolves, stirring gently as needed to dissolve sugar evenly (about 3 minutes).

Continue cooking 4 minutes or until golden (do not stir).  Immediately pour into prepared cake pan, tipping pan quickly to coat bottom.  Arrange apple slices in concentric circles over warm caramel in pan.  Sprinkle with nuts (and spice); set aside.

To prepare cake, weight or lightly spoon flour into dry measuring cups; level with a knife.  Combine flour, baking powder, and salt; stir with a whisk.
Combine 2/3 cup sugar and butter in a large bowl; beat with a mixer at medium speed until light and fluffy.  Add egg yolks and vanilla to sugar mixture; beat until combined.

Add flour mixture and milk alternately to sugar mixture, beginning and ending with flour mixture; mix after each addition.

Place egg whites in a large, clean bowl.  Beat egg whites with a mixer at high speed until stiff peaks form using clean, dry beaters.

Gently fold egg whites into batter.  Spread batter over apples.

 Bake at 350 degrees for 35 minutes or until a wooden pick inserted in the center comes out clean.  Cool in pan 5 minutes on a wire rack.  Loosen cake from sides of pan with a knife; invert cake onto a serving plate.  Serve warm or at room temperature.

Enjoy!