Topping: Measure 2/3 cup of dry cake mix into med size bowl. Cut in butter to fine crumbs thorougly mix in brown sugar and nuts. In lge bowl beat eggs, add sour cream stir until blended. Add remaining cake mix beat according to pkg instructions. Pour 1/2 of the batter in a greased 13x9x2 inch pan. Sprinkle 1/2 of the topping over batter, gently spread remaining batter over topping. Sprinkle remaining topping on top. Bake in preheated oven at 350°F for 40-45 minutes