Preheat Oven and Prepare Baking Sheet: Preheat your oven to 375°F (190°C).

Grease a baking sheet with a little beef tallow or butter to prevent sticking.

Mix Meatball Mixture: In a large bowl, combine the ground beef, ground pork, egg, and salt. Mix thoroughly until all ingredients are well incorporated.

Form Meatballs with Cheese Center: Take a small portion of the meat mixture and flatten it in your hand.

Place a cube of cheese in the center, then fold the meat around the cheese, rolling it between your palms to form a ball. Ensure the cheese is completely encased by the meat to prevent it from leaking out during baking.

Repeat with the remaining meat mixture and cheese cubes.

Bake: Arrange the meatballs on the prepared baking sheet, spacing them evenly.

Bake in the preheated oven for 20-25 minutes, or until the meatballs are cooked through and nicely browned on the outside. The internal temperature should reach at least 160°F (71°C) for beef and pork.

Serve: Remove the meatballs from the oven and let them rest for a few minutes before serving. The cheese inside will be hot and melted, creating a deliciously gooey center.