This is an adaptation of a sour cream coffee cake. I had picked up some Greek yogurt at the grocery store and decided to see what it was like and what I could do with it. Substitute sour cream or regular unflavored yogurt, if you wish. Also, you can substitute all-purpose flour for the cake flour, but take out 1 tablespoon per cup.
GREEK YOGURT COFFEE CAKE
2 eggs
1/2 cup butter
1 cup sugar
1 tsp vanilla extract
2 cups cake flour
1 tsp baking powder
1 tsp baking soda
1 cup Greek yogurt
Preheat the oven to 350F.
Put the first four ingredients in a food processor, and process on a low setting until it is smooth.
Add 1/2 of the flour and 1/2 cup of the yogurt into the food processor, and process on low until incorporated. Add the rest of the flour and yogurt, and process until smooth. The batter will be thick, so you'll likely have to turn up the speed a bit.
Liberally lubricate a springform pan, and put the batter into it. Smooth the batter, and arrange the apple slices on the top. Put into the oven and back for 45-55 minutes, or until a toothpick or skewer comes out clean.
Cool for 10 minutes before removing the side of the pan, then cool another 30 minutes until serving.