ROSEMARY-ROASTED BUFFALO TENDERLOIN WITH GORGONZOLA BUTTER

Steps:

• Discard Gorgonzola rind and in a small bowl stir together cheese and butter until smooth. On a sheet of plastic wrap form Gorgonzola butter into a log about 4 inches long. Chill log, wrapped in plastic wrap, until firm, at least 1 hour. Butter may be made 1 week ahead.
• Preheat oven to 450°F.
• In a 12-inch heavy skillet (preferably cast-iron) heat 1 1/2 tablespoons oil over moderately high heat until hot but not smoking and sear half of steaks until browned, about 2 minutes on each side, transferring to a shallow baking pan. Sear remaining steaks in remaining 1 1/2 tablespoons oil in same manner.
• When steaks are just cool enough to handle, spread tops and sides with mustard and sprinkle with rosemary, pepper, and salt to taste. Roast steaks in middle of oven 8 minutes for medium-rare (coating should just begin to brown). Transfer steaks to a cutting board and let stand about 3 minutes. Cut butter into about 20 thin slices.
• Cut each steak in half horizontally. Tuck a butter slice between steak halves and top steaks with another butter slice.