1. Preheat the oven and prepare your muffin tin: Start by preheating your oven to 375 F (190 C). Lightly grease a 12-cup standard muffin tin. This ensures your meatloaf muffins won’t stick and will release easily after baking.

2. Combine the meatloaf mixture: In a large mixing bowl, gently combine the ground beef, egg, breadcrumbs, milk, 1/4 cup ketchup, Worcestershire sauce, onion powder, garlic powder, salt, and black pepper. Use your hands to mix everything until just combined. Be careful not to overmix, as this can lead to tough meatloaf.

3. Form the meatloaf bases: Divide the meat mixture into 12 equal portions. Take one portion and press it into the bottom and up the sides of each muffin cup, creating a small well in the center for the cheese. The meat should form a cup shape.

4. Add the cheesy surprise: Place 2-3 cubes of mozzarella cheese into the well of each meatloaf cup. Don’t overfill, or the cheese might burst out too much during baking.

5. Seal the cheese inside: Take another small portion of the meat mixture and gently press it over the cheese, sealing it completely within the meatloaf muffin. Make sure there are no gaps where the cheese can escape.

6. Add the finishing touch: Spread a small amount of extra ketchup over the top of each meatloaf muffin. This will caramelize slightly and add a classic meatloaf glaze.

7. Bake to perfection: Place the muffin tin in the preheated oven and bake for 20-25 minutes, or until the meatloaf muffins are cooked through and reach an internal temperature of 160 F (71 C). The tops should be lightly browned, and the cheese inside should be melted and gooey.

8. Rest and serve: Once baked, remove the muffin tin from the oven and let the meatloaf muffins rest for 5 minutes before carefully removing them from the tin. This resting period allows the juices to redistribute, keeping them moist.