Bethenny's Sour Cream Pound Cake

1 stick butter, softened 1 1/2 cups granulated sugar 1 banana, mashed 1/2 cup nonfat Greek yogurt, such as Fage 1/2 cup fat-free sour cream 3 eggs 3 egg whites 3 cups oat flour 1/2 teaspoon baking soda 1/2 teaspoon baking powder 1/4 teaspoon salt 1 teaspoon vanilla extract cooking spray 3 cups fresh mixed berries 2 tablespoons powdered sugar

Preheat oven 325 degrees. Cream butter and sugar in a bowl with an electric mixer on medium speed for 1 minute or until well-incorporated. Add banana, yogurt and sour cream; beat on low speed until combined. Whisk together eggs and egg whites in a separate bowl. Sift oat flour and the next 3 ingredients (baking soda, baking powder and salt) in a large bowl. Add butter and egg mixtures alternately into oat flour mixture. Add vanilla, and pour batter into 10-inch tube pan coated with cooking spray. Bake 1 hour or until a wooden pick inserted into cake comes out clean. Slice into 12 pieces and serve each slice toasted and topped with 1/4 cup berries and 1/2 teaspoon powdered sugar.