Heat olive oil in a large pot over medium heat. Add onion, carrots, and celery. Season with a pinch of salt and sauté for 6–8 minutes, until softened.
Add garlic and cook for 30 seconds.
Stir in marinara, water, Italian seasoning, garlic powder, and red pepper flakes. Bring to a simmer.
Add the mini meatballs and simmer for 8–10 minutes.
Stir in the Shelbows and cook according to the package directions, until just tender.
Add spinach and Parmesan and stir until the spinach wilts.
Stir in heavy cream, if using. Taste and adjust salt and pepper.
Serve topped with extra Parmesan.
