Begin by dividing the ground beef into four equal portions and gently shape each portion into a patty, ensuring they are slightly larger than the burger buns. Season both sides with salt and black pepper to taste. To maintain tenderness, avoid overworking the meat. Set the patties aside while you prepare the mushrooms.

In a large skillet over medium heat, melt the butter with olive oil until bubbling. Add the sliced mushrooms in a single layer, sautéing for 6–8 minutes until they are deeply browned and tender. If using, stir in Worcestershire sauce for added flavor just before removing from heat.

Preheat your grill or a cast-iron skillet to medium-high heat. Cook the patties for about 3–4 minutes on each side, looking for a brown crust and an internal temperature of 160°F.

In the last minute of cooking, place the slices of Swiss cheese on top of each patty. Cover with a lid to help the cheese melt.

Lightly toast the burger buns on the grill or skillet until they are golden brown to enhance flavor and prevent sogginess.

Assemble the burgers with the toasted buns, juicy patties with melted Swiss cheese, and topped with sautéed mushrooms. Serve hot.