I saw this on a Thanksgiving cooking show. I'm not sure which one. Everybody, including my anti-vegetable son, adored it.
If you want to double this recipe, just make another layer of green beans, sauce, and onion rings.
Preheat oven to 350.4-6 servings
1 lb fresh green beans
2 cups white sauce (2 tb butter, 1/2 onion, 2 garlic cloves, 2 tbl flour, 1 1/2 cup milk, 1/2 cup cream)
1 cup or more shredded gruyere
1 cup or more french fried onion rings
Blanch the green beans in boiling, salted water. Drain and refresh in iced water. Drain.
White sauce - melt butter in saucepan. Add onion and garlic and sautee. Add flour and cook 2 minutes, without browning. Add milk and cream. Bring to a boil, adding salt and pepper to taste.
Place green beans in an ovenproof dish. Add white saice. Add cheese. Top with onions.
Can be made a day or 2 ahead to this point and refrigerated. Pull it out of the fridge an hour before baking or run it in the microwave for a couple of minutes to knock the chill off.
Bake covered 30 minutes. Uncover and bake another 20-30 minutes, until browned and bubbly.