Mac and Cheese Meatloaf Casserole (Family-Size Comfort Bake)

Ingredients

• 1 1/2 lb (680 g) ground beef (80/20)
• 1/2 cup (60 g) breadcrumbs
• 1 large egg, beaten
• 1/4 cup (60 ml) whole milk
• 2 tablespoons ketchup
• 1 tablespoon Worcestershire sauce
• 1/2 small yellow onion, finely diced
• 1 teaspoon garlic powder
• 1 teaspoon salt
• 1/2 teaspoon black pepper
• 12 oz (340 g) elbow macaroni
• 3 tablespoons unsalted butter
• 3 tablespoons all-purpose flour
• 3 cups (720 ml) whole milk, warmed
• 3 cups (340 g) shredded sharp cheddar cheese
• 1 cup (115 g) shredded mozzarella cheese (optional)
• 1/2 teaspoon salt
• 1/4 teaspoon black pepper