Heat oven to 450 degrees F. Place roast in large roasting pan.
Carefully mash together garlic and 1/2 teaspoon salt with side of knife to make paste; place in bowl. Stir in fennel, thyme, pepper, oil, remaining salt. Spread over top of roast.
Roast beef in 450 degree F oven for 15 minutes. Reduce temperature to 350°. Roast until instant-read meat thermometer inserted in thickest part without touching bone registers 120 degrees F, about another 2 hours. Let roast stand 20 minutes.
Pour the pan drippings into a 2-cup measure. Set the roasting pan aside. Skim 2 tablespoons of fat from the drippings and place in a 2-quart saucepan. Skim any remaining fat from the drippings and discard. Add the broth and wine to the roasting pan. Place the pan over medium-high heat; stir up any browned bits from bottom of pan with wooden spoon; add to drippings in measuring cup.
Add shallots to fat in saucepan; cook until softened, 3 minutes. Stir in flour, thyme and salt until smooth. Gradually whisk in drippings. Cook, stirring, until sauce boils and thickens. Remove from heat. Stir in browning sauce if using.
Carve roast. Serve with sauce. Makes 16 servings.