In the meantime, prepare the filling: in a bowl mix the grated Grana Padano Riserva with 1 egg, the breadcrumbs, a pinch of grated nutmeg. Season with salt and pepper.
Roll out the two doughs into two rectangles about 4 mm thick and cut into 1-cm-wide strips, alternating them to create a striped rectangle of yellow and black strips attached together. Roll out the pasta with rolling pin to create a rectangle measuring just a few millimetres thick.