Black and Blue Burger

In a medium bowl, mash together blue cheese and butter. Salt and pepper mixture to taste. Place mixture on plastic wrap and roll up to form a cylinder. Refrigerate until firm (about an hour). After cheese mixture has firmed up, divide ground beef into 4 equal portions and make an indention in the center of each patty. Slice blue cheese mixture into four equal parts and place into patties. Mold ground beef around the cheese mixture to cover. Cook on hot grill or in skillet.