Mix in large bowl shredded cheddar cheese, shredded Monterey Jack cheese, cream cheese, sweet onion, 1 clove garlic, sage, melted 2 teaspoons of butter, salt, and pepper. Stir good; you may have to melt the cream cheese a little.
Mix in small bowl the mayonnaise and mustard, chucked blue cheese, 1 clove of garlic, 2 teaspoons of butter, mix good. Set aside.
3Place Cauliflower in microwave and cook until tender, not too large. Place them in a large oven bake dish. Mix in the sauce and ½ of the cheese top, spread remaining cheese on top. Cover and bake for 25 minutes, then remove cover and bake for an additional 5 minutes.