Preheat the oven to 325 degrees. Grease a bundt cake or tube cake pan and line with foil. Grease the foil.
Mix 2 tablespoons of the sugar with ¼ teaspoon of the cinnamon; set aside to use for topping.
Beat the butter, the remaining sugar and the vanilla on high speed until pale and fluffy. Reduce the speed to medium; add the eggs, one at a time, beating well after each addition. Beat in the sour cream, baking powder, baking soda, salt and the remaining cinnamon. Scrape the sides of the bowl often. With the mixer on low, stir in the flour until it’s nearly all mixed in. Stir in the chocolate chips with a wooden spoon, until the batter is smooth and well mixed.
Spread the batter in the pan. Sprinkle the reserved cinnamon-sugar over the top. Bake until a cake tester inserted in the center of the cake comes out clean, about 1 hour and 10 minutes.
Cool the cake in the pan on a wire rack for 30 minutes. Remove the cake from the pan with the foil still on it and let cool completely on the wire rack. Remove the foil. Makes 12 servings.
Source: "Simply Cakes", Elizabeth Alston, Harper Collins Publishers, 1994