Chop nuts and put in a bowl. Add remaining ingredients and set aside.
Heat oven to 350º. Sift flour, baking powder, baking soda, and salt together in a bowl.
Mix butter, sugar, vanilla and eggs in a bowl until smooth.
Continue mixing and gradually add half the flour mixture and the sour cream.
Blend until smooth and then repeat with the remaining flour and sour cream.
Put 1/2 the batter into a buttered and floured bundt pan. Spread 1/2 the topping over the batter as evenly as possible.
Repeat with remaining batter and topping.
Bake 45-55 minutes or until cake tester comes out clean. Do not over bake.
Cool 10 minutes before removing from pan.