This recipe is super simple but appears to be complex and hard to master.
Make the pasta according to Smitten Kitten's detailed recipe. You can make the day before but not much more than that.
Mix the ricotta, Parmesan, nutmeg, flake salt, and black pepper. Put in a pastry bag with a medium sized plain tip or a large ziplock with the corner cut out.
Carefully crack your eggs, separating the egg yolks from the whites without breaking the yolk. Save the whites to brush the pasta dough to seal the raviolo in the next step.
Roll two sheets of pasta dough out as wide as your pasta machine allows, mine is about 4 or 5 inches, and about two feet long. The pasta sheets should be about 1/16th inch thick.
Cut 16 sections of pasta roughly 4X5 or 5X5 inches. Don't stress too much exact size because you will be trimming it down to a 3.5-inch circle.
Brush one square of pasta with egg whites. Pipe a two-inch ring of ricotta (see pictures) and then place an egg yolk in the center of the ricotta.
Place another square of pasta snuggly over and press the edges. If you have a set of round cutter use one that is about 2.5 inches across and one about 3.5 inches across to finish your raviolo. First, grab the smaller cutter and use the non-sharp backside to gently press around the ricotta filling. This will seal the dough thoroughly and make sure your raviolos do not come apart. Use the larger 3.5-inch cutter to cut a circle. Use a spatula to lift the raviolo and put on a floured tray till you are ready to cook. Repeat with the remaining dough.
Refrigerate raviolo for up to eight hours.
Put the truffle juice into a small sauce pot and let reduce by fifty percent. Add the prosciutto, lemon zest and lemon juice in and lower to a simmer.
Whisk in butter and remove from heat. Taste your sauce and adjust seasonings to your tastes.
Bring a large pot of salted water to a boil. Drop raviolos in and cook for no longer than two minutes. Use a skimmer and put one or two raviolos per person into a warmed bowl.
Add herbs to your sauce and pour over. Shave with as many white truffles as you can and eat.
Egg Yolk Pasta: If you have a favorite recipe then use it. Try Thomas Keller's version posted at a favorite blog Smitten Kitten here: pasta recipe.
Eggs: Use only uber fresh eggs, preferably direct from a farmer. I work with MacFarlane Pheasant Farm in Wisconsin and use their pheasant eggs for this dish. They taste richer and are the perfect size.