In a large bowl, dissolve yeast in warm water. Add the shortening, sugar, salt and 4 cups flour. Beat until smooth. Add the cheeses, garlic powder and onion powder. Stir in enough remaining flour to form a soft dough.
Turn onto a floured surface; knead until smooth and elastic, about 6-8 minutes. Do not let rise. Divide in half; shape into two loaves.
Place in two greased 9-in. x 5-in. loaf pans. Do not let rise. Bake at 350° for 25-30 minutes or until golden brown. Remove from pans to wire racks to cool. Store in the refrigerator. Yield: 2 loaves (16 slices each).