Combine nuts, 1/2 cup sugar, and cinnamon and set aside for topping. Mix flour, baking powder, and salt. Combine sour cream and soda. Cream butter and 2 cups sugar until light and fluffy. Add eggs one at a time, beating well after each addition. Add vanilla. Gradually add flour mixture alternately with sour cream mixture, beginning & ending with flour mixture. Spoon 2/3 of the batter into a greased 10-inch tube pan. Top with 1/2 of the nut mixture. Add remaining batter and nut mixture. Bake at 350 for 1 hour or until cake just begins to pull away from the sides of the pan. Cool in pan 15 minutes. Remove from pan and finish cooling on rack.
For more swirled effect, layer batter and topping in equal thirds, and streak with knife.
From the Dinner Co-op