Heat oven to 400. Spray a 9" deep dish pie pan w/ cooking spray. In bowl, combine 1-1/2 cups cheese and macaroni.
Spoon into pie pan. Place remaining ingredients, except 1/4 cup cheese, into blender. Blend until smooth. Or, place ingredients in lg bowl, and w/ mixer on high, mix until smooth. Pour ingredients over macaroni in pie pan.
Bake 40 min, or until a knife inserted in center comes out clean. Sprinkle w/ remaining cheese, bake 1-2 min, or until cheese is melted. Cut into wedges.