Mushroom Filling
Place diced mushrooms into a skillet.
Drizzle with olive oil.
Add seasonings and worcestershire sauce.
Stir to combine.
Cook over medium heat 5-10 minutes until mushrooms are cooked and sauce is evaporated.
Cheese "Whiz" Sauce
In a small sauce pan melt butter.
Whisk in flour and cover for 1-2 minutes.
Slowly whisk in milk, stirring continually until smooth.
Add in cheese, stir until cheese is melted.
Add seasons and stir to incorporate.
Fried Onions
Heat a 1 teaspoon of olive oil in a small skillet.
Add onion and cook over medium heat, stirring occasionally until cooked desired doneness.
Place mushroom mixture into roll. Top with onions and cheese sauce.