1) Preheat oven to 180 degrees C.
2) Butterfly the beef tenderloin by cutting the beef lengthwise down the center to within 1 cm of other side. Set aside.
3) In a medium skillet, melt butter and cook shallots and mushrooms until tender. Add wine and cook over medium heat for about 5 minutes or until liquid is reduced.
4) To stuff and roll the tenderloin, open (or butterfly) the beef and flatten with a meat mallet. Sprinkle with salt and pepper, to taste. Spoon mushroom mixture down the center of tenderloin. Bring the 2 sides of the tenderloin up around filling to meet. Use butcher string and tie around the roll at 2 cm intervals. Place roll in roasting pan.
5) Bake for 45 minutes for medium-rare. Let stand for 5 minutes before slicing.