Mix all ingredients in a bowl, using your hands to mix thoroughly.
Use a melon ball scooper to form meatball shapes with the mix.
Brown on the stovetop on all sides, about 10 minutes.
Add to slow cooker, along with jarred sauce and other half of onion.
Top with handful of basil.
Cook on high 3-4 hours or low 6-8 hours.
Notes
I’m really into the Trader Joe’s marinara sauce in a can. It’s not overly seasoned and the tomatoes taste excellent. it tastes more authentic than all of the jarred versions I’ve tried.