Preheat oven to 350 degrees F.

Pound the lamb with a meat mallet until it is 1 1/2-inches thick. In a large saute pan with butter on medium heat, add the chanterelles and saute until dark brown in color. Set the mushrooms aside until needed.

Season the interior of the leg with the shallots, salt, and pepper. Lay the chevre and Sauteed mushrooms evenly down the center of the pounded out leg. Roll the leg into the shape of a log and tie with butcher's string to hold the round shape. Season the exterior of the leg with salt and pepper.

In a large saute pan with the olive oil on medium-high heat, sear all sides of the lamb. Place the seared leg onto a wire rack with a baking tray underneath. Place the leg in the oven and roast for approximately 1 hour, or until desired internal temperature has been reached. For rare lamb, roast to an internal temperature of 140 degrees F. and 170 degrees F. for well done.

When the pan is removed from the oven, let the lamb rest for 10 minutes at room temperature before slicing. This will prevent the juices from leaving the lamb and drying out the meat.