Preheat your oven to 375°F (190°C). Line a baking sheet with parchment or foil and lightly grease it.

In a small bowl, combine the breadcrumbs and milk. Let sit for 3-4 minutes until the crumbs absorb the milk.

In a large bowl, add the ground beef, soaked breadcrumbs, egg, diced onion, minced garlic, Worcestershire sauce, ketchup, Dijon mustard (if using), salt, pepper, oregano, and 3/4 cup shredded cheese. Gently mix with clean hands or a fork.

Use a small cookie scoop or spoon to portion out about 1.5-tablespoon portions. Flatten each portion in your palm to form a small patty.

Place a mozzarella cube in the center of each patty and wrap the meat around it, sealing the edges so the cheese stays inside.

Roll into a ball and place on the prepared baking sheet seam-side down.

If you love that sweet-savory top, whisk together 1/4 cup ketchup, brown sugar, and vinegar. Brush a little glaze onto each meatloaf bite before baking, saving some for a final brush.

Bake at 375°F for 18-22 minutes, or until the internal temperature reaches 160°F and the outside is lightly browned.

If you used a glaze, brush one more time halfway through baking.

Let the bites rest for 3 minutes before serving.

Garnish with chopped parsley if you like.