Mix together the flour, baking powder, salt and sugar in a large stainless-steel or glass bowl. Cut butter and margarine into large cubes and, using your hands, work into flour mixture until size of large peas. Then add cheese and buttermilk to make a soft dough. On a well floured surface, roll out dough to 3/4-inch thickness; cut with a 2-inch biscuit cutter. (Will keep for up to 24 hours in the refrigerator before baking.) Bake at 350F until golden brown. Makes about 30 biscuits. PER BISCUIT: 165 calories, 3 g protein, 8 g carbohydrate, 14 g fat (5 g saturated), 15 mg cholesterol, 348 mg sodium, 0 g fiber. From the San Francisco Chronicle, 6/29/92.