Melt the butter and heat the olive oil over medium-high heat in a large skillet. Stir in the Worcestershire Sauce. Add your mushrooms and cook until they start to turn golden brown, approximately 5 minutes. Stir about every 1 ½ minutes. Add the onions and cook until the edges brown and the onions become translucent; approximately 5 minutes. Continue stirring every 1 ½ minutes.
In the final minute, reduce the heat to low and add the minced garlic, stirring continuously. Salt and pepper to taste.
