Preheat oven to 400°F.
Bring large pot full of water to boil (large enough for all cauliflower florets). Carefully place Cauliflower into salted boiling water. Leave in boiling water for 5 minutes. Drain and rinse with cold water.
Layer florets into a 9″x 13″ casserole dish. Pour Ranch dressing over top. Sprinkle shredded cheese and sprinkle breadcrumbs evenly.
Bake for 30 minutes or until golden brown and cheese has melted.