Broccoli Casserole

1 head of broccoli
1/2 cup mayo
1/2 cup grated cheddar
cream of mushroom soup
1 egg
1/2 cup chopped onion
panko bread crumbs
1/4 cup butter melted
few butter cubes

Steam broccoli (5 to 7 minutes). Mix all ingredients except panko. Pour into cassrole dish. Mix panko, butter cubes and some cheese together. Sprinkle on top. Bakes at 350 F for 45 min or until brown.