Heat a large, heavy skillet over high heat for 2 minutes, or until very hot. Season steaks with salt and pepper to taste.
Place steaks in hot skillet and immediately turn down the heat to medium high. Cook for 4 minutes. Turn steaks and cook for an additional 4 to 6 minutes, depending on your tastes. Remove steaks from skillet to a platter and cover with aluminum foil to keep warm.
Remove skillet from heat. Quickly saute the garlic for 1 to 2 minutes in the skillet using residual heat. Return skillet to medium low heat and add Marsala and chicken broth. Bring to a boil and reduce for 3 minutes.
Remove pan from heat and whisk in butter and rosemary. Serve sauce over steaks.