Preheat the oven to bake at 400 degrees and prepare your slowcooker by spraying the inside.
Spray a baking sheet with avocado oil or coconut oil. (I also line ours with aluminum foil first)
Mix all the ingredients into a large bowl.
Carefully form the meat mixture into meatballs. There should be enough to make about 16 medium-sized meatballs.
Bake the meatballs in the oven for 12 minutes (They will still be pink on the inside, but that is okay).
Carefully transfer the meatballs to the slowcooker and add one large jar of Rao's marinara sauce. Cook on low for 4 hours. (We let ours simmer for an additional 4 hours until we were ready for dinner)