Preheat oven to 350 degrees. Line a flat baking sheet with parchment paper.
In a large bowl add ground beef, onion powder, egg, bread crumbs, garlic, Worcestershire, salt, pepper, couple dashes of Italian seasoning. Mix thoroughly. Shape into 1-inch balls. Push in to the mixture a cube of cheese. Reshape the meatball. Place on lined baking sheet. Do this until all of the meatballs have been formed.
Bake in the oven until browned, about 15 to 20 minutes. If the cheese cube that was used is too big it will melt out of the meatball.
In a slow cooker, on medium heat add the tomato sauce, crushed tomatoes, Italian seasonings (to taste) onion, and garlic. Keep hot while the meatballs cook. Add the meatballs once they are done cooking. Serve with toothpicks. The sauce can be heated on stove top.