Add the meatball ingredients to a bowl, and knead until well combined.
Form the meat mixture into evenly sized 2-3 inch round meatballs.
Heat the olive oil in a large skillet over medium high heat.
Sear the meatballs on all sides, and place into the bottom of the crock pot.
Melt the butter in another skillet, and saute the onions until softened.
Add the onions and remaining sauce ingredients to a bowl, and spoon over the meatballs in the crock pot.
Place the lid on the crockpot and cook on high for 3 hours.
Notes
Jar Sauce: Short on time? Tomato sauce from a jar works fine.
Different Seasonings: Try using different seasonings for your meatballs, such as garlic salt or red pepper flakes. Or whatever your personal taste.
Different Cheese: Instead of parmesan cheese, you can use Romano or Pecorino.
Sausage: Try this recipe with different varieties of sausage meat. You can use sweet sausage, hot Italian sausage, or mild Italian sausage. Additionally, you can make ground turkey or pork sausage meatballs.
Cocktail Size: If you have a party coming up, you can make these into cocktail meatballs by making them smaller.
Breadcrumbs: Try covering these delicious meatballs in panko bread crumbs for a different texture.
Parsley: Garnish these tender meatballs with fresh parsley, or use oregano instead of parsley if you don't have any.