Step 1

If you are mixing by hand, combine the flour and chestnuts on a work surface. Form them into a mound and make a well in the center. Add the eggs and oil to the well and, using your fingertips, gradually mix in more and more of the flour until most of it is incorporated. On a work surface lightly dusted with flour, knead the pasta for about 10 minutes, or until the dough is firm and elastic, adding more flour if the dough is too sticky. Wrap in plastic wrap and let rest at room temperature for 30 minutes, during which time the dough will soften.

Step 2

If you are using a food processor, combine the flour and chestnuts, keep the motor running and slowly add the eggs and oil, mixing until it just comes together. (If you overwork the mixture it will become too warm.) On a work surface lightly dusted with flour, knead the pasta for about 10 minutes, or until the dough is firm and elastic, adding more flour if the dough is too sticky. Wrap in plastic wrap and toss in the fridge for 1 hour or overnight, during which time the dough will become much more flexible.

Step 3

Unwrap the dough and return it to a lightly floured surface. Line a rimmed baking sheet with parchment paper and sprinkle it with semolina or "00" flour. Press the dough gently to flatten. Cut the dough in half and roll each portion through a pasta machine several times, starting at the thickest setting and ending at the thinnest. (If you don’t own a pasta machine, use a rolling pin to roll it as thin as you can.) Using a knife or a pizza wheel, cut each sheet of pasta into 2-inch (5 cm) diamond-shaped rags. Place the pasta rags on the baking sheet sprinkled with semolina and let rest at room temperature for 10 minutes. (At this point you can cover and refrigerate the pasta rags for up to 3 days.)

Step 4

Using a knife or a pizza wheel, cut each sheet of pasta into 2-inch (5 cm) diamond-shaped rags. Place the pasta rags on the baking sheet sprinkled with semolina and let rest at room temperature for 10 minutes. (At this point you can cover and refrigerate the pasta rags for up to 3 days.)

Step 5

Heat the olive oil in a large pan and cook the mushrooms over medium-high heat until they’ve released their liquid and are golden brown at the edges. Most of the liquid should have evaporated by now. Season with salt and pepper and set aside.

Step 6

If using whole Brussels sprouts, halve or quarter them, depending on their size. Melt the butter in a large pan over medium heat and warm the sprouts and chestnuts until heated through and tender.

Step 7

Cook the pasta in a large pan of generously salted boiling water until al dente, 1 to 2 minutes. (I always salt the cooking water, rather than the pasta dough.) Toss the mushrooms, Brussels sprouts, and chestnuts with the pasta rags and the sage browned butter, season with salt and pepper, and strew some shaved Parmesan over the top.