Cream together shortening, sugar and vanilla. Beat in eggs one at a time. Sift together flour, baking powder and baking soda. Add half to creamed mixture. Beat in sour cream then rest of flour mixture.
Spread half the batter in a greased 9x9" pan. Cream butter, brown sugar and cinnamon. Mix in nuts. Spread half of nut/sugar mixture over batter, cover with additional batter and remaining sugar mixture.
Bake at 350F for 40-50 minutes or until the center passes the toothpick test. Allow to cool for 10 minutes before removing from pan.