Preheat the oven to 350 degrees and spray the tube pan with non-stick spray.
In a small bowl, combine topping ingredients and set aside.
In an electric mixer with a paddle attachment, combine butter and sugar. Cream until fluffy (about 5 minutes).
Add eggs and vanilla. Mix until just combined.
In a separate bowl, combine dry ingredients.
Add 1/2 of the dry ingredients to the butter mixture. Mix on low/medium speed until combined.
Add ½ of the sour cream. Mix until incorporated.
Add the other half of the dry ingredient mixture. Mix on low/medium speed until just combined.
Add the remaining sour cream mixture. Mix until combined.
Pour half of the cake mixture in the tube pan.
Spread half of the topping mixture evenly over the batter.
Add the other half of the cake mixture to the pan.
Spread the remaining topping mixture evenly over the batter.
Bake for 40-45 minutes or until a toothpick comes out clean.
Allow cake to cool before removing it from pan (about 45 - 60 minutes).