Preheat the oven to 400 degrees Fahrenheit.
Finely dice the onion and add to a large mixing bowl with all ingredients aside from the egg.
Mix well with a spoon.
Whisk up the egg in a small dish and add to the bowl with the turkey. Mix together until well combined.
Use a 1.5 tablespoon scoop and roll into balls.
Place on a baking sheet lined with parchment paper. You should end up with 16 meatballs.
Bake for 22-30 minutes or until golden brown. Check the inside of one and make sure it is cooked all the way through.
Remove from the oven and transfer to a skillet with tomato sauce of choice. If you're going to be freezing these, freeze without sauce.
Serve with spaghetti, with zucchini noodles or enjoy as is!
