Make the Ravioli Dough: In a large bowl, mix the flour and salt. Make a well in the center and add the eggs and olive oil. Gradually mix the flour into the eggs and oil until a dough forms.

Knead the dough on a floured surface until smooth and elastic, about 10 minutes. Wrap in plastic wrap and let rest for 30 minutes.

Prepare the Pumpkin Filling: In a bowl, combine the pumpkin puree, grated Parmesan, nutmeg, salt, and pepper. Mix until smooth and adjust seasoning to taste.

Roll and Fill the Ravioli: Divide the dough into four pieces. Roll out each piece on a floured surface into a thin sheet.

Place teaspoons of the pumpkin filling about 2 inches apart over half of the pasta sheet. Fold the other half over the filling and press down around the edges to seal, making sure to remove any air pockets.

Cut between the mounds of filling to form individual raviolis. Press the edges with a fork to ensure they are sealed.

Cook the Ravioli: Bring a large pot of salted water to a boil. Cook the ravioli in batches to avoid overcrowding, about 4 minutes per batch or until they float to the surface. Remove with a slotted spoon and drain.

Make the Hazelnut Cream Sauce: While the ravioli cooks, heat the butter in a saucepan over medium heat. Add the crushed hazelnuts and sauté until lightly browned and fragrant, about 3 minutes.

Lower the heat and add the heavy cream, stirring constantly until the sauce thickens slightly. Stir in the grated Parmesan cheese and season with salt and pepper.

Serve: Place the cooked ravioli on plates and spoon over the hazelnut cream sauce. Serve immediately, garnished with extra Parmesan and a sprinkle of crushed hazelnuts.