Trim fat from pork roast. In an oven-safe pot cook leeks and whole garlic cloves in hot oil until leeks are tender and begin to brown. Push leeks and garlic to the side of pot. Add roast to pan. Brown well on all sides.
Add the milk, salt, and pepper to pot. Bake, covered, in a 400 degree F oven for about 45 minutes or until tender.
Transfer roast to a warm serving platter. For sauce, strain pan juices. Skim off any fat. Reserve 2 cups of the cooking liquid and return to pot. Gradually stir cold water into flour. Stir into cooking liquid. Cook and stir until thickened and bubbly. Cook and stir 1 minute more. To serve, slice meat and serve with fettuccine and sauce. Makes 6 servings.