Advance preparation. split fresh broccoli spears lengthwise, cut into pieces. (Or use frozen broccoli cuts.) Cook in boiling salted water till tender Drain. Cook onions in bolling, salted water till tender Drain.
In saucepan melt 2 TBS of the butter, blend in flour, [1/4 tsp salt], [dash pepper]. Add milk, cook and stir until thick and bubbly.
Reduce heat blend in cream cheese till smooth. Place vegetables in 1 1/2 qt casserole. Pour sauce over mix lightly. Top with cheddar; cover and chill. Melt remaining butter:, toss wfh bread crumbs. Cover, chill.
Before serving, bake casserole covered at 350"F for 30 minutes. Sprinkle crumbs all over, bake uncovered till heated through, about 30 minutes more. Serves 6
Thanksgiving - 2x-4x Batch