Cook pasta according to package instructions and save some salty pasta water.
Heat butter and oil in a large sauté pan over medium heat.
Once butter is melted, add mushrooms and stir to coat in butter/oil.
Cook mushrooms undisturbed for about 6 minutes, then stir and continue cooking undisturbed until they have released all their moisture and are nicely browned.
Add garlic, shallot, thyme, and red pepper flakes. Stir and cook until garlic is fragrant and shallot is softened.
Add white wine, stir while scraping the bottom of the pan, and cook 1-2 minutes until alcohol has cooked off.
Add vegetable broth and mascarpone cheese, stirring until cheese has melted.
Turn heat down to low and simmer until sauce is creamy and thick.
Add cooked pasta and toss to coat each noodle in sauce.
If sauce is too thick, add a bit of pasta water. Taste and adjust seasoning.
Top with grated parmesan if desired and serve immediately.
