Spray a skillet with oil and add meatballs. Cook over medium heat until brown, about 3 - 5 minutes. Remove from skillet.
Spray a saucepan with oil and add onion. Cook for 8 minutes. Add garlic and cook for 30 seconds. Add meatballs, crushed tomatoes, tomato paste, Italian seasoning, sea salt and black pepper. Simmer for 30 minutes, until the flavors combine.
Meanwhile, cook pasta according to package directions.
Drain pasta. Transfer to serving plates and spoon spaghetti and meatballs on top.