Scalloped Sweet Potatoes Recipe

Ingredients

• 3 pounds medium sweet potatoes, peeled and sliced 1/8-in. thick
• 2 tablespoons butter
• 1/2 medium onion, finely chopped
• 3 garlic cloves, minced
• 2 tablespoons all-purpose flour
• 1 cup whole milk
• 3/4 cup heavy whipping cream
• 1 teaspoon salt
• 1/4 teaspoon pepper
• 1/8 teaspoon cayenne pepper
• 1/8 teaspoon ground cinnamon
• 1/2 cup shredded Parmesan cheese
• 2 cups shredded Gruyere cheese, divided