Easter Morning Cinnamon Swirl Bundt Coffee Cake

1 c sour cream
3/4 c butter or margarine
1 1/2 c sugar
2 1/2 c all-purpose flour
1/2 c chopped nuts
1 t baking soda
1 t baking powder
1 t vanilla extract
3 eggs
1 T ground cinnamon
1/4 c sugar

Preheat oven to 400 degrees. Lightly grease one 10 inch bundt pan. Cream 1 1/2 cups sugar together with eggs until well blended. Add sour cream and butter or margarine and beat well. Add flour, baking soda, and baking powder and mix well. Stir in vanilla and the nuts. Mix the remaining 1/4 cup of sugar with the cinnamon. Pour half of the batter into the prepared pan. Sprinkle generously with the cinnamon sugar mixture. Cover with remaining cake batter. Bake at 400 degrees for 8 minutes. Lower heat to 350 degrees and bake for an additional 40 minutes.
Note: Raisins or chopped dates can be added.