Combine 1/2 cup milk and flour in a saucepan, whisking until well blended. Place pan on medium heat and gradually stir in remaining milk. Stir in mustard and nutmeg. Bring to a boil then reduce heat to medium- low, and cook 5 minutes or until mixture begins to thicken; stirring constantly. Stir in S&P; cook 1 minute. Add pasta and shrimp, cheese and chopped basil, tossing gently to combine. Sprinkle with nuts and torn basil.