Place the oats in a small bowl and pour ¼ cup water over them. Stir and let soak while you proceed with the recipe.
Peel and chop a large clove of garlic and set it aside for the meatballs. Peel and slice six cloves of garlic and chop the onion. Heat the olive oil in a 6-quart pot on medium-high. Add the onions and cook until soft (around five minutes), stirring occasionally. During the last two minutes, add the garlic slices to the pan and stir them to combine with the onions.
After the onions are soft, add the cans of tomatoes to the pot. Mash the peeled tomatoes with a potato masher to break them up. Stir to combine and add the bay leaves, salt and pepper. Stir to combine.
When the sauce comes to a boil, lower the heat and loosely cover the pot with a lid, using a wooden spoon resting on the edges of the pan to keep the lid propped open a bit.
Place a large spoon within reach of the pot so you can use it soon for the meatballs. In a large bowl, lightly beat the egg with a fork and add the parsley, chopped garlic, Parmesan, salt, pepper, and the oats/water mixture. Add the meat to the bowl and mix all the ingredients gently with your hands.
Shape the mixture into meatballs about two inches wide. Use the large spoon to gently place the meatballs into the sauce. Wash your hands well and stir the sauce gently with the wooden spoon, being careful not to break the meatballs. Wash the wooden spoon and rest it again on the rim of the pot, so it props the lid. (Do not taste the sauce until the meatballs are fully cooked.)
Stir the sauce occasionally to prevent sticking, being sure to gently scrape along the bottom of the pot. After 35 minutes, check to see if the meatballs are done by cutting into the largest one. The interior should not have any pink. If it is cooked through, the sauce can be tasted going forward. Using a slotted spoon, transfer the cooked meatballs to a serving bowl and cover with foil. Continue cooking the sauce for another 20 minutes.
Serve the gluten-free meatballs and sauce over pasta (use gluten-free if needed) or spaghetti squash. Store leftover sauce and meatballs in the refrigerator for up to four days, or freeze separately. (See notes.)
Video
Notes
If you need these meatballs to be gluten-free, you must use gluten-free oats.
Ground Meat
If using ground turkey, dark meat will provide the most flavor (and fat). But you can make healthier meatballs with lean, white meat.
If you use lean, ground white-meat turkey, you'll need to add an extra 2-4 tablespoons of olive oil to the sauce to give it more flavor, unless you prefer a low-fat option.
Freezing them:
You can freeze these meatballs, either raw or cooked. If freezing them after they're cooked, let them cool off first.
First, flash-freeze the meatballs on a sheet pan for at least an hour. Then transfer them to a freezer bag.
You also can freeze the sauce, separately, in a plastic quart container.
To thaw raw meatballs, place them in the refrigerator overnight. Then you can make the sauce and cook the meatballs in it as directed.