In a small non-stick fry pan, cook the beef patty on both sides until browned and caramelised. Top with cheese, remove from the pan and place under a grill until the cheese is melted.
In the same pan, prepare the creamy mushroom sauce. Sauté mushrooms in the pan juices until browned, then add thickened cream, salt, and pepper. Simmer until the sauce thickens.
To assemble the burger, place the cooked beef patty on the base of the bun, top with red onion, bread and butter pickles, rocket and tomato. Drizzle with the creamy mushroom sauce.
Add the top of the bun and serve immediately for best results.
