Preheat oven to 350 degrees. In large bowl, cream the butter and sugars together. Add eggs, sour cream, baking powder, salt, soda and vanilla. Gradually add flour and mix until the flour is incorporated into the wet ingredients. Add milk to thin batter.
Mix all topping ingredients. Grease two medium size loaf pans. Spread 1/4 of the batter into each pan. Layer the topping on top of the batter, reserving some for the top of the loaf. Spread the rest of the batter into each pan. Finish with remaining topping. Bake for 35 minutes, or until knife comes out clean.