Preparation / Directions:
Grease a 3 to 4 quart casserole. In a large pot of boiling salted water, cook the macaroni for 6 minutes; drain well.
Melt the butter in a large saucepan; whisk in the flour. Slowly add the milk and cook, stirring until thickened. Stir in the mozzarella and 3 cups cheddar; add the Worcestershire sauce and mustard.
Mix pasta with the sauce in the casserole. Top with the remaining cheddar. Bake at 350F for 45 minutes. Garnish with parsley.
DO-AHEAD TIPS: Cool, unbaked, then cover with foil and refrigerate for up to l day before baking. Freeze, baked, up to 1 month. Defrost in the refrigerator; reheat for 50 minutes.