Preheat the oven to 350 F. Cook the broccoli according to package directions. In a large casserole dish, combine broccoli with cream of mushroom soup, milk, salt, and pepper.
Fold in 1/2 of the french fried onions. Sprinkle with shredded cheddar cheese and pepper jack cheese. Top with the remaining fried onions. Bake for 25-30 minutes.