Heat the olive oil in a large pot over medium heat. Add garlic and onion, cooking until softened.
Stir in the mushrooms and cook until golden brown.
Add the tortellini, cream, salt, pepper, and a splash of water. Bring to a gentle simmer.
Cook for 7 to 10 minutes, stirring occasionally, until the tortellini are tender and the sauce has thickened.
Toss in the spinach and cook just until wilted.
Stir in parmesan cheese until the sauce becomes creamy. Taste and adjust seasoning.
Serve hot with extra parmesan sprinkled on top.