Preheat the oven to 450 degrees F. Toss the bell pepper halves with 1 tablespoon olive oil and 1/2 teaspoon salt in a large microwave-safe bowl. Cover and microwave until the peppers soften, 10 to 12 minutes.
Meanwhile, mix the ragu, couscous, raisins, 1/2 cup cheese, 3 teaspoons vinegar, the parsley and 1/4 teaspoon salt in a bowl.
Whisk the remaining 1 tablespoon olive oil and 1 teaspoon vinegar, the tomato paste and 3/4 cup water in the bottom of a large nonreactive baking dish. Carefully transfer the peppers, cut-side up, to the baking dish and fill with the couscous mixture. Sprinkle with the remaining 1/4 cup cheese.
Cover the dish with foil and bake until the peppers are tender and the filling is hot, about 20 minutes. Transfer to plates and drizzle with the cooking liquid from the dish.
Pulse the onion, celery, carrot, garlic and rosemary in a food processor until finely chopped.
Heat the olive oil in a large saucepan over medium-high heat. Add the chopped vegetables and cook, stirring, until softened and golden, 3 to 5 minutes. Add the veal, 1 teaspoon salt and 1/2 teaspoon pepper and cook, breaking up the meat with a wooden spoon, until no longer pink, about 3 minutes. Add the tomatoes, milk, 1 cup water and 1/2 teaspoon salt. Bring to a boil, then reduce the heat and simmer until slightly thickened, about 20 minutes.
Meanwhile, bring a large pot of salted water to a boil and cook the fettuccine as the label directs. Drain the pasta, then toss with half of the ragu (about 3 cups). Top with parmesan. Reserve the remaining ragu to make stuffed peppers.
Per serving: Calories 484; Fat 12 g (Saturated 3 g); Cholesterol 48 mg; Sodium 462 mg; Carbohydrate 71 g; Fiber 5 g; Protein 25 g
Recipe courtesy Food Network Magazine