Preheat oven to 400°F. Melt 6 tablespoons butter in a medium saucepan and cook onions over low heat for 15 minutes, or until tender but not browned. Add zucchini and cook, cov-ered, for 10 minutes, or until tender. Add the salt, pepper, and nutmeg and cook uncovered for 5 minutes.
Stir in flour. Add hot milk and ½ cup Gruyère cheese; cook over low heat for a few minutes until mixture thickens and cheese is melted. Pour mixture into an 8x11x2-inch baking dish. Combine bread crumbs with remaining ¼ cup Gruyère cheese and sprinkle over zucchini mix-ture. Dot with 1 tablespoon butter cut into small bits. Bake for 20 minutes or until bubbly and nicely browned.
TIP: Because of their similar flavors, Swiss cheese can be substituted for the Gruyère.
This Zucchini Gratin recipe is from the 101 Things To Do With A Casserole Cookbook. Download this Cookbook today.