Cream butter, sugar and vanilla extract.
Add eggs singly, beating after each.
Sift flour, baking powder and baking soda. Add to creamed mixture alternately with sour cream.
Spread half of batter in tube pan.
Dot half of filling on batter in pan. (Leave some filling for the top.)
Cover with remaining batter, dot with remaining filling mixture.
Bake at 350°F for 50 minutes.
Remove from oven, and cool for 10 minutes.
Remove from pan, and serve.