In a bowl, combine the ground chicken, spinach, bread crumbs, onion, Parmesan cheese, salt, pepper, garlic and egg. Mix until combined.
Form the mixture into 1 inch meatballs (I like to use a cookie scoop).
Heat olive oil in a skillet over medium-high heat.
Add the meatballs to an oven safe pan in a single layer.
Cook, turning occasionally, until all sides are browned.
Add marinara.
Sprinkle mozzarella & additional tablespoon of Parmesan cheese over the top.
Bake at 400F for about 10 minutes until the cheese is melted and the meatballs are cooked through.
Serve!
