How to Make It
In a large bowl, combine the flour and salt. In another bowl, beat the egg yolks with the whole eggs and cream. Stir the egg mixture into the flour until a dough forms. Knead and shape the dough into a smooth ball. Flatten the dough into a disk, wrap in plastic wrap and let rest at room temperature for 1 hour.
Cut the dough into quarters. On a lightly floured work surface, roll out one-quarter of the dough 1/8 inch thick. Cut the dough into 3-inch-wide strips. Cut each strip crosswise into 1/8-inch-wide noodles and transfer to a baking sheet. Repeat with the remaining dough.
Bring a large pot of salted water to a boil. Add the noodles and cook until tender, about 4 minutes; drain. Add the butter to the pot and melt over low heat. Add the noodles and celery leaves and toss well. Season with salt and pepper and serve at once.