Ingredient:

• 5 tablespoons butter, divided
• 3 pounds Vidalia onions, sliced into 1/4-in. rings
• 2 teaspoons packed brown sugar
• 1 teaspoon dried thyme
• 1 teaspoon garlic powder
• 1 teaspoon salt
• 1/2 teaspoon smoked paprika
• 1/2 teaspoon dried oregano
• 1/2 teaspoon ground mustard
• 1/4 teaspoon pepper
• 1/4 teaspoon cayenne pepper
• 1-1/4 cups shredded mozzarella cheese
• 1-1/4 cups shredded cheddar cheese
• 3/4 cup grated Parmesan cheese
• Handful fresh parsley, chopped