Saute the cheesesteak meat in a skillet over medium high heat until cooked through. Remove and set aside.
Leave 2 Tbsp of the drippings in the skillet, and discard the rest.
Reduce the heat to medium, and add the onions and peppers to the skillet. Saute until they are just beginning to soften.
Stir in the mushrooms, and continue to saute until all of the vegetables are softened.
Mix in the garlic, worcestershire sauce, the cooked meat and salt and pepper to taste.
Lay a tortilla in the bottom of a new skillet over medium heat.
Add ⅓ of the cheesesteak mixture to the tortilla.
Sprinkle with ⅓ of the cheese.
Top with another tortilla.
Saute until the tortilla on the bottom is browned and crispy. Carefully flip the quesadilla over and continue to cook until the other side is browned and crispy too.
Repeat steps 6-10 to create two more quesadillas.
Slice the quesadillas in half to serve.