Don't be stuck on the "keto friendly" bit. These are just good and basic meatballs, but without bread filler. They stick together just fine with the egg and grated cheese. They go great in meatball subs with mozzarella cheese melted over.
FOR THE MEATBALLS
1 lb. ground beef (or 1/2 lb beef and 1/2 lb ground pork)
1 clove garlic, minced
1/2 c. shredded mozzarella
1/4 c. freshly grated Parmesan, plus more for serving
2 tbsp. freshly chopped parsley
1 large egg, beaten
1 tsp. kosher salt
1/2 tsp. freshly ground black pepper
2 tbsp. extra-virgin olive oil
FOR THE SAUCE
1 medium onion, chopped
2 cloves garlic, minced
1 (28-oz.) can crushed tomatoes
1 tsp. dried oregano
Freshly ground black pepper
(Pinch of pepper flakes if you want a bit of spice)
In a large bowl combine beef, garlic, mozzarella, Parmesan, parsley, egg, salt, and pepper. Form into 16 meatballs.
In a large skillet over medium heat, heat oil. Add meatballs and cook, turning occasionally, until golden on all sides, about 10 minutes.
Remove from skillet and place on a paper towel-lined plate.
To the same skillet, add onion and cook until soft, 5 minutes. Add garlic and cook until fragrant, 1 minute more. Add tomatoes and oregano and season with salt and pepper.
Add meatballs back to skillet, cover and simmer until sauce has thickened, 15 minutes. Garnish with Parmesan before serving.