Chestnut and Ricotta Ravioli

Directions

1. For the filling: If using pre-cooked and peeled chestnuts, skip to next step. If using fresh chestnuts in their shells, you need to first rinse and boil them. Cut a slash across the shells on one side (if you happen to cook chestnuts often, there is also a tool that you can buy to help you do this! See headnote). Then place in a pot full of cold water to cover by a couple of inches. Bring to boil and cook about 30 minutes or until tender: Try opening one and inserting a knife into it, it should give way like a cooked potato. Drain and let cool a little before peeling.
2. Mash or crush the cooked chestnuts. Combine in a bowl with the ricotta, Parmesan, egg, nutmeg, 1/2 teaspoon of fennel seeds, and a pinch of salt.
3. To make the pasta dough: Put the flour on a clean flat surface (or in a bowl) and make a well in the center. Crack the egg in the well, add the yolks. With a fork, begin to whisk the eggs, incorporating the flour little by little until you can no longer whisk with the fork. Use floured hands to combine the rest of the flour. Knead for a few minutes or until smooth. Wrap in plastic and let it rest at least 30 minutes at room temperature.
4. To make the pasta, cut the dough into 4 even pieces. Take one piece of dough (keep the rest of the dough covered with a tea towel or plastic wrap so it doesn't dry out) and roll it out using a pasta machine, working down to the most narrow setting. The dough should be thin enough so that you can begin to see your hand through it, but not too thin that it can't support the ricotta filling.
5. Working on a lightly-floured surface with strips of pasta about 4 inches (10 centimeters) wide and as long as you like, place the filling (use 1 level teaspoon) onto the pasta sheet slightly off centre and no more than 1 inch (2 1/2 centimeters) apart. Beat the reserved egg white and brush it around the filling. Fold the pasta in half widthwise (making it skinnier) to meet the edge of the pasta sheet, and press down gently around each spoonful of filling, working from one side to the other, pushing the air out as you work your way around the filling. Be careful not to trap too much air, as the ravioli can burst when cooking.
6. With a fluted pastry wheel cutter or a sharp knife, trim the length of the whole sheet of pasta on the open side (not the folded side), then separate each ravioli by trimming evenly so that you have about a 1/3-inch border around the filling. (You can save the trimmed pieces, knead them together, and continue using them; cover when not in use to avoid drying.) Continue until you finish the pasta and filling—or whichever comes first.
7. Place the finished ravioli on a baking sheet or flat surface lined with parchment paper, and keep them covered with a tea towel while make the others. They will dry out somewhat the longer you leave them, and this is perfectly fine, but if you are leaving them for a significant amount of time, keep them in the fridge. Once you've made all the ravioli, cook in a saucepan of salted, boiling water over a medium heat until al dente, about 5 minutes.
8. Meanwhile, prepare a sauce by toasting the remaining 1 teaspoon fennel seeds in a wide skillet for 1 minute. Then add the butter and allow it to melt entirely, infusing with the fennel seeds. Add about 1/4 cup of the pasta cooking water and swirl the pan or whisk the liquid until the sauce becomes well-combined, essentially emulsified, and thick.
9. When the ravioli are ready, drain (reserving some water if needed) and add to the sauce. If too dry, you can add a little more of the pasta cooking water. Toss gently to coat and then serve immediately with grated Parmesan cheese.