Cranberry Balsamic Pork Tenderloin

3 tablespoons butter
2 8- to 10-ounce pork tenderloin
1-2 chopped shallots
1 tablespoon chopped fresh rosemary
1 cup canned low-salt chicken broth
2/3 cup canned whole berry cranberry sauce
2 tablespoon balsamic vinegar

Preheat oven to 450°F. Melt 1-1/2 tablespoon butter in heavy large ovenproof skillet over medium-high heat. Sprinkle pork with salt and pepper. Sear pork on all sides, about 2 minutes. Place skillet with pork in oven. Roast pork until thermometer inserted into center registers 155°F, about 10 minutes. Meanwhile, melt remaining 1 1/2 tablespoon butter in heavy medium skillet over medium-high heat. Add shallots and rosemary; sauté until onion softens, about 3 minutes. Add broth, cranberry sauce and vinegar and whisk until cranberry sauce melts, about 2 minutes. Transfer pork to work surface. Scrape any juices from large skillet into cranberry mixture. Boil until sauce has reduced enough to coat spoon thickly, about 6 minutes. Season with salt and pepper. Slice pork and serve with sauce.