Remove the stem and leaves from the head of cauliflower. Then cut the head into small pieces. There should be about 4 cups of florets.
Place a steamer basket into a large pot. put the florets onto the basket and then add enough water to cover the bottom of the pot. Bring to a boil and then reduce heat to a simmer. Cover and cook until the cauliflower is tender, about 7-8 minutes.
Add the steamed cauliflower, cream cheese, blue cheese, sour cream, hot sauce, and ranch mix to a food processor. Puree until smooth, but with a few chunks. Check the seasoning and add salt and pepper to taste. Give everything one more whirl.
Spread the cauliflower mixture in a 2-quart baking dish. Sprinkle cheddar cheese all over the top of the dip.
Bake for 20 minutes or until the cheese is melted. Remove from the oven. Sprinkle the top with sliced green onions and serve warm.