Preheat the oven to 375 degrees F (190 degrees C).
Fill a large pot with water and Salt (1/2 teaspoon). Bring to a boil, add the Rigatoni (1 package). Follow package instructions and boil until the noodles are al dente. Drain noodles and transfer to a baking sheet, arranging noodles into 1 flat layer so they keep their shape.
In a high speed blender, add the Pumpkin (2 cup) and Water (3 cup), blend until smooth and creamy.
Add the Vegan Mozzarella Cheese (1 package), Vegan Provolone Cheese (1 package), Vegan Butter (1/4 cup), Ground Nutmeg (1/4 teaspoon), Sage Leaves (4), and Corn Starch (2 tablespoon).
Start by blending on low and gradually turn up the speed until you are left with a smooth and creamy sauce, scraping down the sides and moving everything around as needed.
Prepare a 12-inch springform pan by rubbing with a bit of butter. Arrange the rigatoni noodles vertically in the springform pan. Evenly pour the cheese sauce over the noodles, using a spoon to get all of the sauce out of the blender and to make sure the noodles on the edges get filled as well.
Add the entire bag of Vegan Mozzarella Cheese (1 package) to the top of the rigatoni pie and bake, uncovered, for about 30 minutes until pie is hot and bubbling.
Remove the pie from the oven and while it cools at room temperature, melt Vegan Butter (2 tablespoon) in a small saucepan over medium heat, add the Sage Leaves (12) and cook until crisp, about 2 minutes.
Top rigatoni pie with crispy sage leaves, run a knife along the edge of the springform pan, remove the outer ring of the pan, slice and serve.