In a large pot, heat the oil over medium heat.

Add the onion, carrot, and celery and cook until softened, about 4-5 minutes, stirring frequently.

Add the garlic and cook for an additional 1-2 minutes.

Add the broth, crushed tomatoes, Italian seasoning, salt and pepper and bring to a boil. Turn down to a simmer and allow to cook for 10 minutes.

Use an immersion blender to puree the soup, then add the mini pasta shells and cook until al dente, about 10 minutes.

Remove the soup from the heat, then stir in the spinach. The heat of the soup will be enough to wilt the spinach.

Serve immediately.