Heat olive oil in a large, heavy-based pan over medium-high heat.
Add onion and garlic; cook for 2–3 minutes until softened.
Add tomatoes and cook for 2 minutes, gently pressing them to release juices.
Stir in stock and tomato paste; cook for 1 minute.
Add cream, parmesan, and black pepper. Bring to a gentle simmer.
Stir in spinach until just wilted.
Add the tortellini directly to the sauce and gently stir to coat.
Reduce heat to low, cover, and cook for 2 minutes until pasta is tender.
Serve immediately with extra parmesan and optional chili oil.