Preheat oven to 350. Coat a 9 inch springform pan with cooking spray. Mix chocolate chips, brown sugar, and walnuts in small bowl. Mix the flour, baking powder, baking soda and cinnamon in a medium bowl. Cream the sour cream, butter, sugar and eggs in a large bowl til blended. Mix in the vanilla. Add flour mixture, beating til thoroughly mixed. Layer the batter and chocolate chip mixture, 1/2 at a time, in the springform pan, ending with the chocolate chip mixture. Bake for 40 to 45 minutes or til a wooden pick inserted in center comes out clean. Makes 10 to 12 servings.