Heat oven to 350. Lightly spray a bundt pan w/ cooking spray. In lg bowl, cream butter, 2 cups sugar and vanilla. Add eggs, one at a time, beating well.
In another bowl combine flour, baking powder, baking soda and salt. Add flour mix to butter mix alternately w/ sour cream. Beat until smooth.
Spoon 1/2 the batter into pan. In another bowl, combine 3/4 cup sugar, cinnamon and walnuts. Sprinkle 1/3 nut mix over batter. Pour remaining batter over nut mix. Sprinkle w/ remaining nut mix. Bake 1 hr, or until a toothpick inserted in center comes out clean.