- Heat olive oil in a medium skillet over medium-high heat. Add mushrooms and a pinch of both salt and pepper. Sauté for 4-5 minutes until liquid is released and mushrooms are cooked through. Set aside.
- In a bowl, gently combine beef, onion, garlic powder, salt and pepper. Divide beef mixture into 4 equal portions shaping each into a 4-inch oval patty about a ¼-inch thick (similar to the shape and size of your bread).
- Heat 1 tablespoon olive oil in a large nonstick skillet over medium-high heat. Cook patties, pressing gently, until browned but still pink in the center about 2 minutes on each side. Transfer to a plate.
- Wipe out skillet and reduce heat to medium. Spread the outside of each bread slice with 1 teaspoon mayonnaise. Assemble patty melts in this order: 1 slice bread (mayo-side-down), 1 slice TomaTruffle, ¼ of reserved sautéed mushrooms, patty, 1 slice TomaTruffle, 1 slice bread (mayo-side-up). Repeat with remaining ingredients.
- Place patty melts in skillet. Cook until bottom slice is golden brown, about 2-3 minutes, pressing down firmly with a spatula as they cook. Flip and cook the other side in the same way until cheese is melted.
- Serve immediately.
Note: This is a great use for a panini press if you have one. Just assemble the patty melts then put in the panini press to finish cooking.
