Mushroom Swiss Burger

Ingredients (19)

• 2 lbs ground sirloin
• 4 tbsp Perfect BBQ rub
• 4 tbsp Worcestershire sauce
• 4 hamburger buns
• 4 tbsp unsalted butter
• 8 slices Swiss cheese
• FOR THE MUSHROOM SAUCE:
• 2 tbsp olive oil
• 2 tbsp unsalted butter
• ¼ cup onion
• 1 tbsp thyme
• ½ tsp Kosher salt
• ¼ tsp black pepper
• 1 lb mushrooms
• 1 tbsp Worcestershire sauce
• ¼ cup red wine
• 2 tbsp all-purpose flour
• 1 cup beef stock
• 2 tbsp heavy cream