Try this Invisible Egg Yolk Ravioli recipe, or contribute your own.
Encasing a liquid egg yolk inside pasta requires precise moisture control, or the dough will dissolve before cooking finishes. Fresh lasagna sheets provide a thin, pliable wall, but they absorb ambient humidity rapidly; keep unshaped disks under a damp kitchen towel at room temperature until assembly. Drainage is paramount for the ricotta filling. Whey left inside the cheese will liquefy further upon heating, breaching the pasta seal and releasing the yolk prematurely.
Forming a secure bond demands clean edges. Brushing reserved egg white exclusively along the perimeter creates a protein-based glue when compressed with a fork tines. Avoid overfilling the ricotta nest; the yolk must sit securely in the center without spilling over the dairy barrier. When transferring the formed parcels into simmering water maintained at 180 degrees Fahrenheit, use a perforated slotted spoon to support the base uniformly.
Cooking demands absolute vigilance because fresh pasta finishes in roughly 60 seconds of gentle water contact. Leaving the parcels submerged longer overcooks the interior yolk, turning a fluid sauce into a solid sphere. Swapping fat-free ricotta for whole-milk ricotta yields a richer mouthfeel, though moisture levels must be squeezed out through cheesecloth for ten minutes beforehand to prevent structural failure during the boil.