Mash 4 tablespoons butter with the parsley, chives, lemon zest, lemon juice and mustard in a small bowl with a fork. Scoop the butter mixture onto a sheet of plastic wrap. Wrap up and form into a 3-inch log. Refrigerate until firm, about 30 minutes. Preheat the oven to 450˚. Generously season the steaks on both sides with salt and pepper. Wrap each steak around the edge with a slice of bacon and secure with a toothpick. Heat the olive oil and remaining 1 tablespoon butter in a medium cast-iron skillet over medium-high heat. When the butter melts, add the steaks to the skillet and sear until golden brown, about 1 minute per side. Transfer the skillet to the oven and cook 7 to 10 minutes for medium rare. Let rest 5 minutes before serving. Serve with a slice or two of the cowboy butter on top.