Trim crusts from bread. Place bread in a shallow dish; pour milk over bread. Let stand 5 minutes. Place bread mixture in a food processor; add basil and next 6 ingredients (basil through garlic). Set aside without processing.
Cook pasta according to package directions, omitting salt and fat. Drain in a colander over a bowl, reserving 3 tablespoons cooking liquid. Place pasta in a large bowl. Add reserved cooking liquid to basil mixture in food processor, and process until smooth. Add the pesto to pasta; toss well to coat. Sprinkle with parsley, if desired. Serve immediately.