Cauliflower casserole 
https://www.justapinch.com/recipes/side/vegetable/cauliflower-casserole.html

Ingredients For cauliflower casserole

    1 head of cauliflower (or 2 packages frozen cauliflower)
    1 can cream of mushroom soup, 10.5 oz
    1 1/2 c melted Velveeta cheese
    1 can french fried onions

Cook cauliflower until tender. Drain. Break into smaller pieces.

In a large casserole dish, add cauliflower, mushroom soup, and melted Velveeta cheese. Top with french fried onions.

Bake at 300F for 30-35 minutes.