Melt 2 tablespoons butter in a saucepan over medium-high heat. Add garlic and shallot, then 1 cup broth, Port and cranberries. Boil liquid until reduced to 1/2 cup, about 8 minutes. Set sauce aside.
Melt remaining 2 tablespoons butter in a large skillet over medium-high heat. Sprinkle steaks with salt and pepper. Add steaks to skillet; cook to desired doneness, about 5 minutes per side for medium rare. Transfer steaks to a plate; cover loosely with foil and keep warm . Add rosemary to skillet, then add sauce and remaining 1/4 cup broth. Boil 1 minute, scraping up browned bits. Season with salt and pepper and spoon sauce over steaks. Top each with cheese.