3 gratin adapted from julia child Recipes

onion, finely chopped, butter, flour, boiling milk , cream or 1 cup half-and-half, dry white wine (optional) or 1/4 cup vermouth (optional), juice , from salmon can (if any), salt, pepper, dried oregano, canned salmon, flaked (a few small chunks are ok), grated swiss cheese or 1/4 cup gruyere cheese, mushrooms , sauteed in their own juice (optional) or lemon juice (optional)

onions, minced (2 lb), butter (or try using less ), flour, eggs or 3 egg yolks, milk , cream or 2/3 cup half-and-half, salt (or to taste), pepper, nutmeg, grated swiss cheese or 1/2 cup gruyere cheese, pastry shells (optional see note below )