For the topping, mix margarine, flour, and brown sugar with fork until crumbly. Stir in the half cup of chocolate chips and nuts. Gradually add flour mixture alternately with sour cream to mixture. Fold in the other half cup chocolate chips. Spread into greased 33 cm x 23 cm pan.Sprinkle topping evenly and bake at 180ÂșC for 45-50 minutes. Source Given to my by Peggy Weseman 7-1-95 ----