In a greased 2-quart casserole pan, layer onions, 2/3 of cheese and pepper to taste.
In a sauce pan, heat soup, milk and soy sauce, stirring to blend. Pour soup mixture in a casserole.
Top with bread slices. Bake at 350 uncovered for 15 minutes, until bread is golden brown.
Push bread slices under the sauce and top with the remaining cheese.
Bake for 15 more minutes.