Preheat oven to 475°.
Heat a small skillet over medium heat with 2 tablespoons olive oil; when oil is hot, add the bell pepper, half the onion, celery, and carrots; stir/saute 5 minutes; season with salt and pepper, then remove to a plate to cool.
In a bowl, combine the sausage and ground beef with the egg, bread crumbs, cheese, and cooled sauteed vegetables; mix well.
Form 4 large oval-shaped patties no more than 1 ¼ inches thick; arrange patties on a cookie sheet.
Drizzle patties with a little olive oil; bake 17-18 minutes, until cooked through.
Heat a saucepan over med-high heat; add a drizzle of olive oil, and then add the pancetta.
Let the pancetta crisp up a bit and render its fat, then add the remaining chopped onion and the garlic; cook 8-10 minutes, until tender.
Stir in the beef stock and tomatoes; season the sauce heavily with ground black pepper.
Add in the Worcestershire sauce and hot sauce; decrease heat to low.
Serve meatloaf patties topped with the Italian barbecue sauce and a green salad alongside, if desired.