Spray a springform cake pan or Bundt pan with nonstick spray.
Using an electric mixer, cream together butter and 2 cups of sugar. Add eggs one at a time, then add sour cream and vanilla extract and mix until blended. In a separate bowl, mix together flour, baking powder, and salt. Mix dry ingredients into wet ingredients until blended.
I another bowl, combine remaining 3/4 c sugar, brown sugar, cinnamon.
Pour half of the batter into the cake pan. Sprinkle with half of the cinnamon sugar mixture. Add remaining batter to pan and top with the rest of the cinnamon sugar. Bake 50-60 minutes, or until a cake tester comes out clean. Let cool slightly and sift powder sugar over the top.