In a large skillet, melt butter. Add mushrooms and garlic and cook over medium-high heat until tender.
Add spinach, cream, and tomatoes. Bring mixture to a boil and cook for about 5 minutes (or until thickened) while continuing to stir gently.
Meanwhile, cook tortellini according to directions on package (usually only 3-5 minutes). When tortellini is done, remove with a sieve or slotted spoon and add to the skillet.
Stir in 1/4 cup of Parmesan cheese and the pine nuts.
Serve pasta garnished with the remaining 1/4 cup Parmesan cheese.