Preheat oven to 425°, then line a medium baking sheet with aluminum foil and grease with cooking spray.
Drain chickpeas, reserving liquid. Transfer chickpeas to a food processor and process until broken down.
Make chia egg: Combine chia seeds and water in a medium bowl and stir to combine. Let sit 5 minutes, until mixture gels and becomes thick.
Add chia egg, oats, tomato paste, basil, garlic, fennel seeds, and red pepper flakes into the food processor and blend until combined. If mixture is too dry, add liquid from chickpea can 1 tablespoon at a time until desired consistency is reached. Season with salt and pepper.
Form mixture into 16 meatballs and place on prepared baking sheet. Bake for 10 minutes, flip meatballs, and bake 8 to 10 minutes more, until golden and crisp. Serve with your favorite pasta and sauce.