For the Sauce:
Combine sauce ingredients in bowl and set aside.
Melt 3 Tbls. butter in large, high walled skillet over medium heat. Add diced onions and sauté about 10-15 minutes, until they become soft and golden.
Add remaining butter, garlic and mushrooms. Continue to cook until the mushrooms have released their liquid and become richly colored, about 10-15 minutes.
Add wine sauce mixture and bring to boil, reduce heat to medium and cook about 5-10 more minutes.
Cook pasta according to package directions. Drain, then add pasta to the sauce and toss to combine. Add salt and pepper to taste. Top with chopped parsley and grated Parmesan cheese.
To make this recipe plant-based, simply substitute the butter, oyster sauce and parmesan cheese with your favorite plant-based version.