In a large mixing bowl, combine the ground beef, crushed pork rinds, beaten egg, Worcestershire sauce, garlic powder, onion powder, salt, and pepper. Mix by hand until just incorporated; do not overwork the meat.

Divide the mixture into 4 equal portions and shape into oval patties approximately 3/4-inch thick.

Heat a large cast-iron or heavy-bottomed skillet over medium-high heat. Place patties in the dry skillet (the fat from the beef will render) and sear for 4-5 minutes per side until a dark brown crust forms and internal temperature reaches 160°F (71°C).

Remove the patties from the skillet and set aside on a warm plate. Drain all but 1 tablespoon of the rendered fat from the pan.

Add 2 tablespoons of butter to the skillet. Once melted, add the sliced mushrooms and sauté for 5-6 minutes until they have released their moisture and turned golden brown.

Pour in the beef broth and heavy cream, using a spatula to scrape up the browned bits (fond) from the bottom of the pan. Bring to a light simmer.

Slowly sprinkle the xanthan gum over the surface of the sauce while whisking vigorously to prevent clumping. Continue to simmer for 2-3 minutes until the gravy reaches a coating consistency.

Return the beef patties and any collected juices to the skillet. Spoon the gravy over the patties and simmer for 1 minute to reheat.

Garnish with minced parsley and serve immediately.