Wrap a slice of bacon around each fillet, fasten with a toothpick (wooden). Let stand at room temperature for 30 minutes. Sprinkle with black pepper, place on broiler rack. Spread 1/2 butter on fillets and broil in preheated broiler for about 8 minutes. Use remainder of butter on fillets when you turn them. Broil to preferred doneness and serve with sauteed mushrooms if desired. Serves 6.