Mix Walnuts, 1/2 cup of sugar and Cinnamon in small bowl
Mix sour cream and baking soda in small bowl
Sift together Flour, baking powder and salt
Blend Butter and 1 cup of sugar, then add eggs and vanilla
Alternate adding flour mixture and sour cream mixture to blended mixture (butter, sugar etc). Pour half of the final dough mixture into a greased angel food pan. Add half of the cinnamon mixture on top, then pour the rest of the mixture on top (layering) Finish the top with the cinammon mixture. Cut through with a knife to marbelize. Bake at 350 degrees F for 45 minutes or longer if needed. Check top for firmness. Take out of oven and let cool upside down for 10 minutes. Lift pan off and let cool for additional 10-15 minutes before slicing.