dice green onion, place in a food processor, and pulse until finely chopped. Add milk, seasonings, and butter, pulse again until creamy
Place frozen cauliflower and broccoli into a 9 x 13 glass baking dish, mix in cream of mushroom soup, green onion mixture, and 1/2 pkg of cheese. Sprinkle remaining cheese on top, and sprinkle breadcrumbs on top
Bake at 350 degrees F. for 30 min (or until cheese is melted, and top is golden brown.)
Boil Penne Pasta, drain. Serve casserole over penne pasta.