Melt butter in a large skillet. Season pork with salt and pepper and brown on all sides over medium-high heat. Remove from skillet and add pears; cook for a few minutes to brown. Add pork back to skillet with all ingredients except rosemary. Tent with foil and cook for 30 minutes or until pork reaches 155°F internally. Let stand for 5 minutes before slicing. Transfer to a platter and sprinkle with rosemary.