red food coloring powder (or gel and you may need a little more flour); I used this.
If you don't want to use food coloring you can get colored pasta with vegetables etc.
PROCEDURE
With the Planetary Mixer: prepare the fresh pasta by placing the ingredients in the planetary mixer fitted with the leaf and knead until you obtain a smooth dough.
By hand: create a well with the flours on the pastry board and break the egg into the center. With the prongs of a fork, beat the egg, gradually incorporating the flour taken from the well. Continue to knead by hand for about 10 minutes until the dough is smooth and homogeneous. Wrap the two doughs separately in cling film. Let rest for half an hour.
Roll out the dough by hand with a rolling pin or with a pasta machine to the penultimate thickness or your preferred thickness.
Two methods to have pasta with stars.
1) in the photo: cut the yellow pastry with a small star-shaped cookie cutter. Place the perforated yellow pastry on top of the red pastry. Roll the rolling pin to make it stick well (gently but so that it doesn't come off during cooking). If the pastry is already dry on the surface, you can moisten the surface with water using a kitchen brush. Cut out the pappardelle with a serrated pastry cutter or the pappardelle die of the pasta machine.
2) or cut out the red pastry with a small star-shaped cookie cutter. Place the red stars on the yellow pastry. Roll the rolling pin to secure them and then run the pastry through the pasta machine once. You can invert the colors, of course. Cut out the pappardelle with a serrated wheel or using the pappardelle die on the pasta machine.