Preheat oven to 425°F.

Line a standard rimmed sheet pan with foil. Spray with nonstick baking spray; set pan aside.

Using a large skillet, add olive oil and place over medium-high heat. Once hot, add onion, celery and bell pepper; cook for 5-6 minutes, stirring often. Add minced garlic and cook for 1-2 more minutes.

Using a large bowl, add onion mixture, ground beef, Worcestershire sauce, breadcrumbs, ketchup, Italian seasonings and egg; stir until just combined.

Place a 4” round cookie cutter on the prepared pan. (Note: If you don’t have a 4” round cutter, you can also use a tuna can with the top and bottom removed.)

Divide the meatloaf mixture into 7 equal parts. Working with one portion at a time, wrap meatloaf around one of the squares of mozzarella. Note: Take care to wrap the cheese entirely so it doesn’t melt out while baking! Gently press mixture into the cookie cutter on the tray. Remove the cookie cutter and repeat process with the remaining portions of meatloaf.

Using a small mixing bowl, combine all Glaze ingredients (ketchup, mustard, brown sugar and Worcestershire sauce). Spread mixture evenly on top of meatloaves.

Bake for 10 minutes at 425°F. Reduce temperature to 325°F and continue baking for 15-20 more minutes, or until internal temperature of meatloaf reaches 160°F.

{Optional} Garnish with chopped Italian parsley and serve over hot marinara sauce.