01Preheat oven to 375°F and lightly coat a casserole dish with 2 tablespoons butter. Combine sharp cheddar and Monterey Jack in small mixing bowl.
02Bring large pot of water to boil, and chop cauliflower into small florets. Once water is boiling, add cauliflower to pot and cook for approximately 5 minutes, until cauliflower is firm but tender. Strain and set aside in large mixing bowl.
03Heat remaining butter in large saucepan over medium-high heat. Add milk and heavy cream. Stir in garlic powder, onion powder and salt and pepper, to taste. While continuing to whisk, add 1/2 cup of cheese mixture. Continue stirring until sauce is smooth.
04Pour cheese sauce over cauliflower and stir to combine. Transfer mixture to prepared casserole dish. Scatter remaining cheese mixture over cauliflower and sprinkle paprika on top to finish.
05Bake for 15 to 20 minutes, until cauliflower is tender. Broil in the oven for the last 1 to 2 minutes for a lightly golden brown color on top. Let cool at least 4 to 5 minutes before cutting and serving.