For the pasta: Pile the flour into a large mound on your work surface. Make a well in the center and add the eggs. Use a fork to whisk them together in the well. Once blended, keep whisking the eggs and slowly whisk in the edges of the flour. Use your hands to fold the eggs and flour all together. While still loose, drizzle in the olive oil and water. Keep kneading together until the dough is smooth, elastic and warm. Wrap the dough in a clean kitchen towel and let rest while you make the filling.
For the filling: Bring 2 pots of water to a boil. Add salt. Break the Swiss chard leaves in half and add them to one pot of boiling water. Cook for 3 minutes. Add the spinach to the second pot of boiling water and cook for 5 minutes. Drain the Swiss chard and spinach well and squeeze out all the water until dry. Chop the leaves very fine. Add to a large mixing bowl along with the raveggiolo cheese, Parmesan, nutmeg, egg and some pepper. Mix together well.
Cut the pasta dough into 4 equal pieces. Roll one piece through a pasta machine, beginning at the widest setting and working your way down. You want the pasta about 1/4-inch thick and in a long but rectangular sheet. Flour your work surface, then lay the pasta sheet on the surface. Drop tablespoonfuls of filling onto the pasta in a row along the bottom quarter of the sheet, leaving a 2-inch space between each tablespoon of filling. Trim the edges with a pasta cutter to make the sheets even. Lightly moisten the edges of the pasta sheet with water. Fold the top half of the dough over the filling. Use your fingers and the side of your hand to press the seams closed and seal the space between each mound of filling. Press the edges closed. Use the pasta cutter to trim into ravioli.
Roll out the remaining 3 sheets of pasta. Add the filling and cut into ravioli.
For the sauce: Melt the butter in a large saute pan. Add the sage and cook until just crisp and fragrant.
Bring a large pot of water to a boil. Add the ravioli in batches, about 10 at a time, and cook until they float, about 1 1/2 minutes per batch. Add the cooked ravioli to the butter sauce, toss gently and add Parmesan to taste.