Melt butter in a saucepan. Add flour and make a paste. Add milk and bouillon cubes. Cook over low heat until thickened. Add pepper to taste. Add more milk when adding the other soup ingredients, depending on the thickness you desire.
To this base you may add steamed broccoli and American cheese; or chunks of baked potato (peel and all) with American cheese, bacon pieces, and chives; or pureed, stewed tomatoes for a bisque; or leeks that have been cleaned well, steamed, and chopped; or cooked asparagus cut in pieces (if canned asparagus is used, add some of the liquid as well), topped with grated cheese and bacon pieces.