Preheat oven to 350F
Coat an 8" springform pan with cooking spray. Dust with 1/2 tsp. of the cocoa.
1/2 tsp. + 3 tbsp. unsweetened cocoa powder
2 oz. semisweet chocolate, chopped
1 cup sugar
1/3 cup fat free sour cream
1 tbsp. butter
1 large egg yolk, at room temperature
1 tsp. vanilla extract
1 tbsp. whole grain pastry flour
4 large egg whites, at room temperature
1/8 tsp. cream of tartar
12 servings
Place the chocolate in a large microwaveable bowl.
Microwave on high power for 1 minute.
Stir until smooth.
Stir in 3/4 cup of the sugar, the sour cream, butter, egg yolk, and vanilla.
Stir in the flour and the remaining 3 tbsp. cocoa.
Place the egg whites and cream of tartar in a large bowl.
Using an electric mixer on high speed, beat until soft peaks form.
Gradually beat in the remaining 1/4 cup sugar until stiff, glossy peaks form.
Genlty stir about 1/3 of the egg whites into the chocolate mixture to lighten it.
Fold in the remaining whites until no white streaks remain.
Pour into the prepared pan and smooth the top.
Bake for 30 minutes, or until a wooden pick inserted in the center comes out with just a few moist crumbs.
Cool on a rack.
The cake will fall as it cools, leaving a raised edge.
Gently press down the edge as it cools.
Remove the pan sides and place on a serving plate.