In a large glass baking dish, add liver and milk and let soak for 20 minutes.

In a large skillet over medium heat, add bacon and butter and cook until fat has rendered, about 6 minutes. Transfer bacon to paper towels to drain and reserve 3 tablespoons fat in skillet. Reserve remaining fat.

Cook onions with salt and pepper, to taste, in bacon fat in skillet over moderate heat for 10 minutes or until caramelized. Transfer onions to a bowl and add bacon. Set aside.

Pat liver dry and discard milk. In a large zip-top bag, add flour, Essence, salt and pepper. Working in batches, add liver and shake to coat. Set aside on baking sheet until ready to cook.

Add 2 tablespoons reserved bacon fat to skillet over high heat and add liver; cook for 2 to 3 minutes on each side. Turn liver over, remove pan from heat, add sherry and beef broth, return pan to heat and shake and flambe. Cook on second side for about 2 minutes or until cooked through. Serve liver with pan sauce, topped with onions and bacon.