Position rack in center of oven and preheat to 350 degrees Fahrenheit.

Generously grease a nine- and- a- half- by four-inch Bundt pan, kugelhopf mold, or fluted tube pan, taking care to butter tube and each fluted section.

Mix cinnamon with three tablespoons sugar in a small bowl.

Sift flour, baking powder and baking soda into a medium bowl.

In another bowl mix sour cream, yogurt and vanilla.

Cream butter in a large bowl with an electric mixer until light. Add one cup sugar and beat until smooth and fluffy. Beat in eggs, one by one. At low speed, stir in flour mixture alternately with sour cream mixture, each in two portions.

Pour slightly less than half the batter into prepared pan. Sprinkle with half the cinnamon sugar.

Gently spoon dollops of batter over mixture, using just enough to cover it. Sprinkle with remaining cinnamon sugar. Gently add remaining batter in dollops over it. Spread gently to cover mixture.

Bake about 55 minutes or until a cake tester inserted in cake’s center comes out clean. Cook in pan on a rack 10 minutes.

Run a thin-bladed flexible knife around tube but not around sides of pan. Invert cake onto a rack and cool completely. Serve at room temperature.