Warm the pot. Set a large soup pot or Dutch oven over medium heat.
Add olive oil or butter and let it heat until shimmering.
Sauté aromatics. Add onion, carrots, and celery with a pinch of salt. Cook 5–7 minutes until softened, stirring occasionally. Add garlic and cook 30 seconds until fragrant.
Build the base. Pour in crushed tomatoes and broth.
Stir in Italian seasoning, red pepper flakes (if using), and a few grinds of black pepper. Bring to a gentle boil.
Add the tortellini. Stir in the tortellini and reduce heat to a simmer. Cook according to package directions, usually 4–7 minutes, until the pasta is tender and floats.
Make it creamy. Lower the heat.
Stir in the cream and Parmesan until smooth. Do not boil after adding dairy; keep it at a gentle simmer.
Finish with greens. Fold in spinach and cook 1–2 minutes until wilted. Taste and adjust seasoning with salt and pepper.
Serve. Ladle into bowls and top with extra Parmesan and fresh herbs if you like.
Add a drizzle of olive oil or a crack of pepper for a simple finish.