4 pkgs. frozen spinach
1 lb. hamburger
1 env. onion soup mix
1/2 pt. sour cream
1 can (4 oz.) mushrooms, stems and pieces
1/2 c. each, grated Cheddar cheese and Monterey Jack cheese (save 1/2 c. of each cheese for top of casserole)

Prepare spinach as directed on package; drain well.

Brown meat and drain; mix soup mix in with meat. Add mushrooms, sour cream and 1/2 cup each cheese; mix well. Add spinach and mix well again.