Preheat oven to 350 degrees F. Coat two 9-by-5-inch loaf pans with cooking spray.Advertisement
Heat oil in a large skillet over medium heat. Add onion and celery; cook, stirring occasionally, until tender, 10 to 12 minutes. Add garlic and cook, stirring, for 1 minute more. Transfer to a large bowl and spread into a thin layer. Let cool for 5 minutes.
Add eggs, breadcrumbs, 6 tablespoons ketchup, parsley, Worcestershire, salt and pepper to the vegetables and stir to combine. Add beef, turkey, pork and sausage; mix with your hands until combined. Divide between the prepared pans.
Bake the meatloaves until an instant-read thermometer inserted in the center registers 160 degrees F, 40 to 45 minutes.
Brush the meatloaves with the remaining 6 tablespoons ketchup. Turn the broiler to high. Broil the meatloaves until the ketchup is bubbling, 3 to 5 minutes. Let stand for 15 minutes before slicing. Garnish with parsley, if desired.
Tip: Try one these ideas for leftover meatloaf.
Breakfast Sandwich: Pan-fry thin slices of meatloaf alongside an egg. Serve on a toasted whole-wheat English muffin with sliced pepper Jack cheese, tomato and onion.
Quick Quesadillas: Layer crumbled meatloaf, shredded cheese and salsa between whole-wheat tortillas and cook in a little oil until the cheese is melted and the tortillas are crispy.
Patty Melt: Place slices of meatloaf on a piece of rye toast. Top with sauerkraut and Gruyère cheese and broil until the cheese melts.
To make ahead: Freeze for up to 3 months.