220g chestnut flour
27g tapioca starch/cornflour/potato flour
25g glutinous rice flour
0.75 tsp xanthan gum
3 large eggs + 1 large egg for egg wash
1 tbsp olive oil
½ tsp salt
Whisk the chestnut flour, tapioca starch, sweet rice flour, and xanthan gum into a large bowl.
Create a well in the middle of the flour and crack three eggs into the well. Add the olive oil and salt.
Use a fork to lightly whisk the eggs together in the middle of the well, then begin mixing it all together with the flour.
Once it's well mixed, use your hands to knead until it forms a dough. If the the mixture feels too dry, add ½ teaspoon of water at a time while kneading.
Knead until dough is smooth and elastic, but not very sticky. If you find it too sticky, add another teaspoon of chestnut flour until it reaches the desired texture.
Roll the dough into a ball, wrap it in plastic, and let it rest in the fridge for 30 minutes.
Bring 4-quarts of water to boil in a large pot with a teaspoon of salt.
After letting the dough rest, cut dough into 6 equal pieces.
Use your hands to press one piece at a time on a chestnut-floured surface until it is about ¼-inch thick, reserving the other pieces in plastic wrap under a towel.
With a pasta roller or rolling pin, roll out each piece into a thin sheet, lightly dusting both sides with chestnut flour as you go. Repeat until it feeds through smooth, then reduce the thickness one stop at a time, dusting the pasta sheet lightly with chestnut flour, until you get to a 4, which is the setting before the pasta begins to get paper thin.
Use a knife or the smooth edge of a pastry wheel to trim the edges of the pasta sheet so they are smooth and the sheet is an even width all the way down, 3-4 inches.
Dust both sides lightly with chestnut flour and set aside, while you repeat with the remaining dough.
Roll the trimmed edges up with the next piece of dough.
Cut into strips for fettuccine or pappardelle.