Coat a large skillet with cooking spray, then saute onions and garlic over medium heat until soft, about 4 minutes.
Add in protein of choice and cook, breaking up, until browned and cooked through.
In a small cup, mix the beef broth, cornstarch, ketchup, mustard, and Worcestershire sauce. Pour into the skillet.
Simmer, mixing often, until meat mixture has reduced a bit, about 3 minutes.
Lower heat and add in cheese. Stir until cheese has melted through, about 4 minutes. Season withe black pepper and kosher salt, to taste.
Serve on toasted brioche buns with your favorite burger toppings.