Fresh Pasta Dough (rolled thinly) - purchased fresh from the deli section in your market or make your own
4Egg Yolks at room temperature (carefully separate yolks from whites)
1cupof left-over Mashed Potatoes (refrigerated) or Ricotta Cheese
1/2cupof freshly grated Parmesan Cheese (plus more for garnishing)
50gof Truffle Butter
Fresh Black Truffle
Fleur de Sel or Sea Salt
Ground White Pepper
For the Filling:
Mix Mashed Potatoes or Ricotta Cheese with grated Parmesan cheese.
Transfer filling to a pipping bag with a 1/2-inch round tip.
For the Raviolo:
Lay your dough flat on a large surface and cut 8 circles using a large round pastry cutter. 4 will be used for the Base (Base dough) and the other 4 will be used to cover the Top of the raviolo (Top dough).
With a smaller round pastry cutter, lightly mark a circle on each of the Base dough. Pipe mashed potato filling around those circles (large enough to fit an egg yolk), using them as a guide until you form a 1-inch circular nest.
Gently place egg yolk in the centre of each nest and season with some salt and pepper. Brush some cold water around each Base dough (outside of the nest) and place the Top dough over the yolk to cover it.
Gently press around the outside of the filling (do not press on the filling itself) towards the edges of the dough to rid of any air pockets. Seal the dough by pressing on the edges. Use another large round pastry cutter to trim off any uneven ends on the dough.
Cooking the Raviolo:
Bring a large pot of water to a boil. Gently place raviolo into the boiling water and let cook for 1-2 minutes.
Heat a small saucepan (medium heat) and place truffle butter in it. Cook until the butter starts to melt and turn off heat once it starts to foam.
Drain raviolo from the pot and place on serving plate. Spoon some melted truffle butter from the saucepan over the raviolo.
Sprinkle some Fleur de Sel and grate some Parmesan cheese and fresh Black Truffles over raviolo.
Recipe adapted & modified from http://www.marthastewart.com/319228/raviolo-with-egg-yolk-truffle-butter