Bring a large pot of well-salted water to a boil over medium heat. Set a bowl of well-salted ice water on the counter. Add the broccoli rabe and cook for 1 minute, remove the broccoli rabe from the boiling water and plunge it immediately into the salted ice water. Reserve the boiling water to cook the pasta. Once the broccoli rabe has cooled, remove it from the ice water and squeeze out any excess water.
Finely chop the broccoli rabe (the food processor works really well here) and put it in a large mixing bowl. Add the ricotta, eggs and Parmigiano and season with salt, to taste. Taste for seasoning and adjust, if needed. Put the filling in a pastry bag and reserve.
Set the pasta roller on the widest setting (#1). Start with half the pasta dough, keep the other half covered until ready to use. Using your hands, flatten the dough as much as you can to facilitate it going through the pasta roller. Run the dough through the roller, twice dusting it in between rolls if it feels sticky. Fold the dough into thirds and turn it 90 degrees (a quarter turn) and run it through the pasta machine 2 to 3 times. Move the roller to the next setting (#2) and run the pasta through. Dust lightly with flour if the dough feels sticky. Continue to run the dough through the machine reducing the opening (or moving the setting to the next larger number) in between every roll. Stop when you get to the correct thinness, this will usually be around number 5 or 6 on the dial, but every machine is different, you will have to be the judge of your own pasta thickness.
*Tip: When rolling out pasta dough, always hold the pasta on the tops of your hands- palms down! If you hold it fingers up you will create stretch marks and those are never good!
To assemble the ravioli:
Lay out the dough on a flat surface. Brush the lower half of the dough (the part that is closest to you) lightly with water. This is the glue that will hold the ravioli together. Use the glue sparingly, if you use too much the pasta will slide and not stick. Pipe 1-inch balls of filling onto the pasta that has been brushed with water, leaving about 2 inches between each ball. Fold the top half of the pasta down over the filling to meet the bottom edge. Using your index fingers, poke around each filling ball to seal the ravioli shut, AND to make sure that there are no air bubbles. Using a fluted round cutter or a fluted pastry wheel or even a drinking glass, cut out each ravioli. Transfer to a sheet tray dusted with semolina or polenta and reserve until ready to use.
To cook the ravioli and make the sauce:
Add the butter to a large saute pan and bring to a medium heat. Add 1 cup of chicken stock and season with salt, to taste. Shake the pan to incorporate the butter and stock and simmer until the stock has reduced a bit and the sauce looks velvety and is the consistency of heavy cream. If the sauce thickens too much, adjust the consistency with chicken stock.
Add the ravioli to the pot of boiling water and cook for 3 to 4 minutes. Carefully remove the ravioli from the cooking water and put them immediately into the sauce. Bring the sauce to a boil shaking frequently to be sure that the ravioli dont stick to the bottom of the pan. Sprinkle with 1 cup of Parmigiano and swirl to combine the cheese with the sauce.
Transfer the ravioli to a serving platter and sprinkle with a little more grated Parmesan. Garnish with chopped pistachios and serve.