Combine ground beef, oats, milk, egg, salt, garlic powder and chili powder in a bowl. Mix using hands or a wooden spoon.
Roll into balls and place in a 9x13 baking dish.
Prepare sauce by combining ketchup, brown sugar, dried onion, garlic powder and liquid smoke until sugar is mixed well.
Evenly distribute sauce over meatballs.
Bake at 350° for approximately 40 minutes. Check to make sure meatballs are done by cutting one in half to see if it's pink, or use a meat thermometer and it should read 160° F.
Notes
You can use regular oats instead of gluten free oats if you aren't sensitive to gluten
You can use evaporated milk instead of nut milk if you aren't sensitive to dairy
Do not skip out on the Liquid Smoke. I believe it's what makes these the BEST meatballs.
You can freeze these by doubling the batch and freezing one immediately. Sauce can be prepared prior to freezing or on the day of cooking.