Preheat the oven: Set to 425°F (220°C).
Line a rimmed baking sheet with parchment or lightly oil it.
Mix the base: In a large bowl, whisk the egg, ricotta, parmesan, garlic, onion powder, oregano, parsley, salt, and pepper until smooth.
Add chicken and crumbs: Add the ground chicken and breadcrumbs. Use a fork or your hands to gently combine. Do not overmix or the meatballs can turn dense.
Form the meatballs: Lightly oil your hands. Scoop about 2 tablespoons per meatball (a small cookie scoop helps) and roll into balls.
You should get 20–24 meatballs. Space them evenly on the tray.
Bake: Place on the center rack and bake 12–15 minutes, until the centers read 165°F (74°C) or the juices run clear. They should be lightly golden.
Warm the sauce: While they bake, heat marinara in a large skillet or pot over medium-low until gently simmering.
Sauce and simmer: Transfer baked meatballs into the marinara.
Simmer 3–5 minutes to let flavors meld. If the sauce thickens too much, add a splash of water.
Serve: Spoon over pasta, spaghetti squash, or greens. Finish with fresh basil, extra parmesan, and red pepper flakes if you like a little heat.