Some preparations swap the tomato sauce for Alfredo or pesto, and even seafood manicotti is a thing. It's highly customizable, but shy away from anything too avant-garde, or the taste and texture ...
However, the sauce seemed waterier than that on the meatless manicotti. Also on the menu ... in a very buttery (yet not excessively decadent) Alfredo sauce. But the gorgonzola and sun-dried ...