**Instructions:**

1. **Prepare the mushrooms** – Sauté mushrooms in butter over medium heat until golden brown and tender. Set aside.
2. **Cook the beef patty** – Mix ground beef with salt, pepper, and Worcestershire sauce. Form patties slightly larger than the bread and cook in a skillet until browned on both sides.
3. **Assemble the sandwich** – Spread a thin layer of mayo on the bread. Place Swiss cheese on both sides, then add the beef patty and sautéed mushrooms.
4. **Grill to perfection** – Heat a skillet and grill the sandwich until the bread is golden brown and crispy, flipping carefully.
5. **Serve hot** – Slice in half and enjoy this gooey, cheesy, crispy delight.