Sauté shallots and garlic in vegan butter with salt and pepper over medium heat until translucent, about 10 minutes, stirring periodically to prevent sticking or burning.
Remove thyme leaves from stems and add to shallots. Continue to sauté for 5 minutes longer.
Add mushrooms to pan and stir to mix with onions. Sauté mushroom mixture over medium heat until browned, about 10 minutes.
Add wine to pan and bring to a boil over high heat before reducing to medium heat and reducing liquid to about one half, about 20 minutes.
Add truffle oil and cashew cream, stirring to combine.
Add vegetable stock only if necessary to achieve desired consistency.
Adjust seasoning to taste and fold into prepared pasta.