3 gratinee lyonnaise onion soup Recipes

unsalted butter or 4 tbsp unsalted margarine, yellow onions, thinly sliced, salt, fresh ground pepper, cognac, beef stock or 8 cups broth, fresh thyme , tied into bundle, french bread , cut into 1/2-inch slices, gruyere cheese , coarsley grated, egg yolks (optional), port wine (optional), chopped parsley, garnish

unsalted butter, yellow onions, thinly sliced, salt, freshly ground black pepper, cognac, beef stock or broth, fresh thyme , tied into a bundle with kitchen string, french bread , cut into 1/2-inch thick slices, gruyere cheese, coarsely grated, egg yolks (optional), port wine (optional), chopped parsley, garnish