Broccoli Au Gratin Recipe

Ingredients

• 4 tablespoons butter
• 1/2 small onion, chopped
• 3 garlic cloves, minced
• 3 tablespoons all-purpose flour
• 2 cups 2% milk
• 1 large bunch fresh broccoli, cut into florets
• 1 cup shredded sharp cheddar cheese
• 1/2 cup grated Parmesan cheese, divided
• 1 teaspoon salt
• 1 teaspoon pepper
• 1/2 teaspoon ground mustard
• 1/8 teaspoon cayenne pepper
• 1/2 cup panko bread crumbs