Preheat the oven to 375° F. Place the squash on a lightly oiled baking sheet and brush with the olive oil. Bake for about 1 hour, or until the flesh is soft when pressed lightly with a spoon. Set aside.

To make the pasta: Divide the dough into four pieces before passing through the pasta machine. Pass the pieces through the thinnest setting on the machine making sure they are at least 6-1/2 inches wide, then trim horizontally into 5-inch wide strips.

Once the squash has cooled, scrape out the flesh and mash in a bowl. Stir in the prosciutto, Parmesan, basil, sage, egg yolk and cream. Season with the nutmeg, salt and pepper. Cover and set aside.

Spoon heaped teaspoons of the squash mixture at 2-1/2-inch intervals along the pasta strips. Lightly brush with water around the edges of the squash. Lay another sheet of pasta on top and press firmly around each mound to expel any air and to seal. Cut out the ravioli by pressing a 2-1/2-inch biscuit cutter down firmly, then flour lightly Place in a single layer between sheets of waxed paper and refrigerate until ready to use.

Bring a large saucepan of salted water to a boil. Add a splash of oil to stop the pasta from sticking and cook the ravioli in batches for 5 - 6 minutes, or until they float and are at dente. Drain well.

To make the herb sauce, melt the butter over low heat, then add the garlic and let infuse for a few minutes. The longer you do this, the stronger the garlic flavor, but take care not to allow the garlic to brown. Take the pan off the heat and remove the garlic with a slotted spoon. Tear the basil and add to the sauce.

Toss the ravioli with the basil sauce to reheat and coat well. Serve on warm plates.