Topping (recipe follows) In large bowl, mix flour, sugar, baking powder, salt, and baking soda. Add starter, oil, egg, raisins and nuts; stir to mix well. Spread in greased and floured 20 cm or 23 cm square pan; sprinkle with topping. Bake in preheated 350 deg. oven, 30 to 35 mins., or until browned and pick inserted in center comes out clean. Cool slightly in pan on rack; cut into squares. Best served warm. Note: The original coffee cake recipe was doubled and baked in a 13 x 9 x 5 cm pan about 45 mins. TOPPING: In a small bowl, mix half C. packed brown sugar,m 1- half tsp. each flour, cinnamon and granulated sugar. Cut in 2 Tbs. butter (or margarine), at room temperature, until crumbly.