Melt butter over med-high heat in a large skillet. Add mushrooms and sauté until they release their juices.
Add garlic and wine. Cook until alcohol scent disappears. Add lemon juice, thyme, salt, and pepper.
Whisk in cream until thoroughly mixed in.
While sauce cooks, prepare tortellini according to package directions. Once tortellini is drained, toss with the sauce. Garnish with Parmesan cheese.