Stir in crumbled blue cheese. Season with salt and pepper to taste.
Lay the butterflied tenderloin open on a work surface. Season the inside with salt and pepper. Spread the mushroom-blue cheese mixture evenly down the center.
Roll the tenderloin back up and tie it securely with kitchen twine every 2 inches. Season the outside with salt and pepper.
Heat remaining olive oil in an ovenproof skillet over medium-high heat. Sear the tenderloin on all sides until browned, about 6–8 minutes total.
Transfer skillet to the preheated oven and roast for 20–25 minutes, or until the internal temperature reaches 130–135°F (55–57°C) for medium-rare.
Remove from oven and let rest for 10 minutes. Slice and serve.
Notes
Let the tenderloin rest before slicing to retain juices.
You can use goat cheese or cream cheese if preferred over blue cheese.
Pairs wonderfully with roasted vegetables or mashed potatoes.