In a bowl, mix together the ricotta cheese, egg, salt, pepper, and Italian seasoning.
Drizzle half of the low carb marinara into the bottom of an oven-safe baking dish that will fit in your air fryer basket. Spread the ricotta mixture into the bottom of the dish on top of the sauce.
Place the thawed meatballs on top of the ricotta blend and add the remaining marinara sauce.
Cover the dish with aluminum foil and air fry the dish for 12 minutes, or until the meatballs are warmed through.
With 4 minutes remaining in the cooking time remove the aluminum foil, sprinkle on mozzarella cheese and cherry tomatoes and place the casserole back in the air fryer to finish.