Cheesy Cauliflower Casserole - HAPPY VEG

Ingredients

• 1 Head Cauliflower, broken down into florets
• 3 Tbsp. Unsalted Butter
• 1 Yellow Onion, chopped
• 3 Tbsp. AP Flour
• 2 C 2% Milk
• 1 C Extra Old Cheddar, shredded
• ½ C Monterey Jack Cheese, shredded
• ½ C Pecorino, shredded
• 1 Tsp. Dry Mustard Powder
• 1 Tsp. Garlic Powder
• ½ Tsp. + Sea Salt
• ¼ Tsp. White Pepper
• 1/8 Tsp. Cayenne Pepper
• Chives - Garnish