Make the Grano filling: Combine 12 cups water, salted as you would for pasta, and Grano in a pot. Bring to a boil, then reduce heat to medium. Simmer, stirring frequently, until Grano is tender but still chewy, about 30-35 minutes. Drain well and cool to room temperature. Process the Grano to a smooth paste with the ricotta in a food processor; a blender will not give the same creamy results.