Bring a large pot of water to a boil. Add the spinach and cook just until wilted and bright green, about 1 minute
Drain the spinach and rinse under cold water. Squeeze well to remove all excess moisture.
Place the spinach in a food processor with the 2 large eggs. Process until the spinach is finely chopped.
Place the flour in a pile on a large work surface and make a well in the center.
Add the pureed spinach to the center of the well along with the 2 egg yolks.
Mix together the puree and egg yolks, then start to bring the flour into the well to incorporate. Knead the dough to form a smooth ball. If too crumbly after a few minutes of kneading, slowly add a little water. If too wet to handle, slowly add a little more flour.
Wrap the ball in plastic or cover with a damp cloth and allow to rest at room temperature for 30 minutes to 1 hour.
Divide the dough into four equal pieces. Place one on floured work surface and cover the remainder.
Roll the dough into a thin sheet using a pasta machine or rolling pin, until it is about 1/16 inch (1.5 millimeters) thick.
Roll through a fettuccine attachment on the pasta machine or cut by hand into ribbons about 1/4 inch (6 millimeters) wide.
Arrange the fettuccine into small nests on a parchment-lined baking sheet or on a pasta drying rack to dry for a few minutes to an hour. Repeat with remaining dough.
Bring a large pot of salted water to a boil. Add the pasta in batches, careful not to overcrowd, and boil until they rise to the surface.
Drain and serve immediately with desired sauce.