Step 1

Preheat the oven to 350°F and lightly grease a 2-quart baking dish.

Step 2

Cook green beans (3 bags) by microwaving them in a microwave-safe bowl for 2-3 minutes -- just to slightly soften them. Drain well by placing them in a kitchen towel and gently wringing out excess liquid. Set aside.

Step 3

Melt butter (6 tablespoons) in a large skillet (large enough to later accommodate all the green beans).  Add onions (1/2 cup) and cook until very tender. Remove saucepan from heat and add in flour (3 tablespoons) and the next 5 ingredients and blend together until smooth paste forms. Add cream (3 cups) and blend until mixture is smooth.  Replace skillet on medium heat and bring mixture to a boil stirring constantly. Add green beans and mix to evenly coat.

Step 4

Pour into a 2-quart casserole dish. Sprinkle casserole with cheese (1-2 cups) then bread crumbs (1 1/2 cups). Bake in preheated oven for 20 minutes or until casserole is heated through to the center.