Sift flour, sugar, baking powder and salt into mixing bowl; stir in brown sugar. Make a well in dry ingredients. In this order, add: salad oil, egg yolks, water and flavoring. Beat until satin smooth. Combine egg whites and cream of tartar in large mixing bowl. Beat until they form very stiff peaks. Pour egg-yolk batter in thin stream over entire surface of egg whites, gently cutting and folding, just till blended. Fold in nuts. Bake in ungreased 10-inch tube pan at 325 degrees for 55 minutes, increase heat to 350 degrees and bake 10-15 minutes more. Invert pan; let cool. Frost with Golden Butter Frosting, recipe below: