Preheat your oven to 375°F (190°C). Prepare a baking sheet by lining it with parchment paper.
Mix the meatloaf ingredients: In a large bowl, combine the ground beef, breadcrumbs, milk, egg, onion, garlic, salt, pepper, and Worcestershire sauce. Mix until well combined.
Form the bites: Take a small portion of the meat mixture, flatten it in your hand, place a small amount of cheddar cheese in the center, and then mold the meat around the cheese to form a ball. Place on the prepared baking sheet. Repeat with the remaining meat and cheese.
Prepare the glaze: In a small bowl, mix together the ketchup and mustard. Brush this mixture over the top of each meatloaf bite.
Bake: Place the baking sheet in the oven and bake for 25-30 minutes, or until the meatloaf bites are cooked through and the tops are caramelized.
Serve: Garnish with additional chopped parsley before serving.