Preheat oven to 325 degrees F. On a cutting board, mash the garlic and 1/2 teaspoon salt together with the flat side of a knife until it turns into a paste. Add the rosemary and continue to mash until incorporated. Put the garlic-rosemary paste in a small bowl and add 2 tablespoons of the oil; stir to combine. Set aside.

Season both sides of the brisket with plenty of salt and pepper. Rub the rosemary-garlic paste over the brisket. Drizzle with additional olive oil. Place a large roasting pan or Dutch oven over medium-high heat. When the pan is hot, place the brisket in the roasting pan and sear to form a nice brown crust on both sides, adding additional oil as necessary to prevent sticking. Lay the vegetables all around the brisket. Add the wine, tomatoes, tomato liquid, parsley, and bay leaves. Cover the pan tightly with a lid or aluminum foil and bake in the preheated oven for 3 to 4 hours, basting every 30 minutes with the pan juices, until the beef is fork-tender.

Remove the brisket from pan and place on a cutting board. Allow brisket to rest for 15 minutes. Remove vegetables from the pan with a slotted spoon; discard vegetables. Skim some of the excess fat from the pan juices, leaving about 1/4 cup fat in the pan; place the roasting pan with the pan juices and fat over medium-high heat. Boil and stir about 5 minutes, until the sauce is reduced by half. (For a thicker sauce, mix the 1 tablespoon flour with the 2 tablespoons water and whisk into the gravy.) Slice brisket and serve with sauce over Parsnip Puree. If you like, garnish each plate with watercress.

Put parsnips in a pot, season with salt, and add garlic and thyme. Cover with the milk and cream. Place pot over medium heat and bring to a simmer. Simmer for 12 to 15 minutes, until tender (the tip of a paring knife should go through parsnip pieces without resistance). Drain parsnips and reserve cooking liquid. Place parsnips in a food processor with butter. Process and add enough of reserved cooking liquid to achieve texture of whipped cream. Season to taste with salt and additional pepper and finish with a drizzle of oil.