Cooking Instructions

• Heat oil in a large skillet over medium. Add onions and ½ teaspoon salt, and cook, stirring often, until deeply golden brown, very soft and jammy, 35 to 45 minutes.
• Add 2 tablespoons sherry to skillet and cook, stirring constantly, until mostly evaporated, 15 to 30 seconds. Remove from heat and set aside until cool enough to handle, about 15 minutes.
• Preheat oven to 350°F with rack in the center position. Finely chop ½ cup caramelized onions and place in a large bowl; set the remaining caramelized onions aside.
• Add panko, eggs, onion soup mix, chopped thyme, pepper, 1 tablespoon Worcestershire sauce, and remaining 1 teaspoon salt to bowl with caramelized onions; stir to combine.
• Add ground beef and ground pork and gently mix with clean hands until evenly combined.
• Divide meat mixture into 6 equal portions (about 8 ounces each); form into 5- x 2-inch meatloaves. Place meatloaves on an aluminum foil-lined baking sheet.
• Bake the meatloaves for 20 minutes. Meanwhile, stir together ketchup, remaining 1 tablespoon Worcestershire sauce, and remaining 2 teaspoons sherry in a small bowl until smooth.
• Remove baking sheet from oven, brush ketchup mixture evenly over tops and sides of meatloaves. Return to oven and continue baking until an instant-read thermometer inserted into thickest portion of meatloaves registers at least 160°F, 5 to 10 minutes.
• Remove baking sheet from oven and turn oven to broil with rack about 7 inches from heat source. Top meatloaves evenly with reserved caramelized onions, and sprinkle evenly with Gruyère (about ¼ cup each). Broil until cheese is melted and starting to brown in spots, 3 to 5 minutes.
• Garnish with additional fresh thyme and black pepper, and serve with mashed potatoes.