Pasta

• ½ cup unbleached all-purpose flour, plus more for dusting
• Salt
• 3 large egg yolks

Filling and Sauce

• 6 ounces robiola fresca cheese, cut into 6 equal pieces
• 6 large eggs
• Salt
• 4 tablespoons unsalted butter
• 1 ounce fresh black truffle
• 6 tablespoons freshly grated Parmigiano-Reggiano or Grana Padano cheese
• Freshly ground white pepper

For pasta:  In a large mixing bowl, whisk together flour and pinch salt. Mound flour mixture and form a well in the center. Add yolks to the well. Using a fork, gently break up yolks and slowly incorporate flour from inside rim of well. Continue until liquid is absorbed, then knead in bowl until dough forms a complete mass. Transfer to a well-floured work surface and knead until smooth and elastic, about 10 minutes more. Wrap dough tightly in plastic and let rest for 30 minutes.

Line a baking sheet with parchment paper and dust with flour. Divide dough into two equal pieces. Turn pasta machine to widest setting. Flatten 1 dough piece to rectangle (cover remaining piece with plastic wrap). Run dough through machine 2 times. Fold uneven ends over to make straight edge. Adjust machine to next narrower setting. Run dough through machine 2 times, dusting lightly with flour if sticky. Cut dough strip in half crosswise for easier handling. Repeat, running dough through machine 2 more times on each narrower setting until pasta is generous 1/16 inch thick (setting #2), dusting lightly with flour if sticky. Repeat with remaining dough piece.

For filling and sauce:  Place dough strips on work surface. Cut strips into twelve 4-inch squares, trimming as needed. Place 1 pasta square on prepared baking sheet. Place 1 piece robiola in center; press center of cheese to form well large enough to hold 1 egg yolk. Carefully break open 1 egg and separate yolk from white (reserve egg white for another use). Gently place egg yolk in well of cheese. Using your finger, lightly dab the inside edges of pasta square with water. Carefully place 1 pasta square atop egg yolk, pressing edges of pasta squares together to seal tightly, enclosing yolk and cheese completely. Dust ravioli lightly with flour. Repeat procedure with remaining pasta, cheese and yolks for a total of 6 ravioli.

Fill a large skillet with 1½ inches of water; sprinkle with salt. Bring water to boil. Working in 2 batches, gently slide ravioli into skillet, egg yolk side up; adjust heat to keep water below rolling boil and cook just until pasta is tender, being careful not to overcook egg yolks, about 2 minutes (do not turn ravioli over).

Using a slotted spoon, transfer ravioli to plates. Melt butter and drizzle over ravioli. Thinly slice and finely grate truffle over the top, sprinkle with cheese and pepper, and serve immediately.