1. Cut the pumpkin into 1-inch thick slices, place them in a baking dish, and bake in a preheated oven at 450°F for 30 minutes. Remove from the oven, let cool completely, then mash in a food processor.
2. Put the pumpkin puree in a mixing bowl; add the grated cheese, crushed cookies, egg, pinch of nutmeg, salt, and pepper. Mix vigorously with a wooden spoon.
3. Roll out the pasta preparation into a thin layer; then, with a pastry cutter, cut out 2-inch squares. Beat the egg white lightly and brush the squares of pasta with it. Place a small amount of pumpkin puree in the center of each square, fold the square, and press the edges together.
4. Cook the pasta in a large quantity of salted water until it is al dente; drain, and place in a serving dish. Melt the butter with the sage leaves in a small saucepan and pour over the pasta. Sprinkle with grated cheese and serve.