Step 1

Preheat oven to 300 degrees F (150 degrees C).

Step 2

Heat olive oil in a skillet over medium-high heat. Season lamb chops with salt and pepper. Sear lamb in hot oil until browned, 1 to 2 minutes per side. Remove chops to a plate to drain, reserving drippings in the skillet.

Step 3

Saute onion and garlic in reserved drippings until tender, about 5 minutes.

Step 4

Transfer drained lamb chops to a baking dish; add onion mixture. Sprinkle rosemary over the chops. Pour beef broth and red wine into the baking dish. Cover dish with aluminum foil.

Step 5

Bake in preheated oven for 3 hours.

Step 6

Remove lamb to a serving platter. Carefully drain liquid from baking dish into a saucepan and place over medium heat. Beat cornstarch and water together in a bowl using a whisk to assure no lumps remain; stir into the liquid in the saucepan. Add Worcestershire sauce and cook until the liquid thickens into a gravy, about 5 minutes.