Preheat oven to 375F. Butterfly the pork loin by using a sharp knife to cut in half length-wise, stopping about 1 inch from the bottom. Lay the loin flat and use a meat mallet to pound out to 1 inch thickness. Set aside for a moment.
In a small bowl, combine goat cheese, rosemary, garlic, and mustard. Season with salt and pepper to taste.
Spread goat cheese mixture to within 1 inch of edges over butterflied pork. Top with halved cranberries and drizzle with honey. Tightly roll up pork loin on the short side and use butchers twine to wrap around and tie in place. Season outside of pork loin well with salt and pepper to taste.
Heat a Dutch oven or a large skillet over medium-high heat, then add butter and olive oil and swirl pan. Sear pork loin 3-5 minutes, gently turning on all sides until a deep golden brown.
Transfer pork loin to a greased 9x13 baking dish. Place in preheated oven and roast at 375F 35-40 minutes until pork loin registers 140F.
Tent pork loin with tin foil and allow to rest 20 minutes. Transfer pork loin to a cutting board and cut into slices. Arrange on a serving plate and serve immediately while warm. Enjoy!