In a food processor or blender, blend half of the silken tofu and soymilk together until creamy. If desired, add more silken tofu. In a large saucepan or skillet, combine the margarine, lemon juice, onion powder, half of the crushed garlic (reserve the other half for the mushrooms), pinch of nutmeg, and salt and pepper, to taste over medium-low heat until hot, stirring often. In a separate small bowl, combine cornstarch and ½ cup cold water. Stir until blended. Once the sauce is hot, add the cornstarch and water mixture and stir until creamy over medium heat (do not let sauce boil again). Once sauce has reached desired thickness, add in fresh parsley and basil (as much or little as you like), salt and pepper (freshly cracked is best for this) to taste, and the cooked pasta. Combine and keep warm over a low heat.