Gruyère Mac & Cheese with Caramelized Onions - Got Milk

Ingredients

• 6 tablespoons – unsalted butter
• 1 – large onion , thinly sliced
• Pinch (to taste) – kosher salt
• 1/4 cup – flour
• 2 1/2 cups – whole milk
• 6 ounces – Gruyère cheese , shredded
• 4 ounces – Swiss cheese , shredded
• 2 ounces – Parmesan cheese , grated
• 8 ounces – medium shells
• 1 teaspoon – sweet paprika
• 1/4 teaspoon – cayenne pepper
• 1/4 teaspoon – ground nutmeg
• 2 teaspoons – Dijon mustard
• Pinch (to taste) – black pepper
• 1/2 cup panko breadcrumbs
• Pair each serving with: 8-ounce glass of milk