Rinse meat and pat dry. In a small bowl, mix thyme, salt, and pepper. Rub mixture evenly all over roast. Set on a rack, bones down, in 10- by 15-inch roasting pan.
Roast beef in a 375° regular or convection oven until a thermometer inserted in the center of the narrow end reaches 135° for medium (the wide end should be about 125° for rare), about 2 1/2 hours. As fat accumulates in pan, ladle it out and discard.
Transfer roast to a platter and let stand in a warm place at least 10 minutes.
Meanwhile, skim off and discard remaining fat from pan drippings. Add beef broth topan and stir to scrape up browned bits. Add brandy. Set pan over high heat and stir until mixture is boiling vigorously. Stir in juices accumulated from roast on platter. Pour sauce through a fine strainer into a small pitcher.
Carve roast and serve with sauce.