Pasta

To make the pasta dough, place the flour on a clean work surface and make a well in the center.

Crack the eggs into the well and add the olive oil and salt. Mix the flour into the egg mixture until a dough forms. Knead the dough for 5-7 minutes until smooth and elastic. Cover with plastic wrap and let rest for 30 minutes.

Filling

While the dough is resting, make the filling by combining the ricotta cheese, Parmesan cheese, egg yolk, salt, and pepper in a bowl. Mix well until smooth.

Assemble

Roll out the pasta dough to about 1/8 inch thickness. Using a round cookie cutter or glass, cut out circles of pasta. Pipe the ricotta filling in the center of each pasta circle leaving a hole for the yolk. Carefully add an egg yolk to each raviolo.

Brush the edges of the pasta circles with water and cover them with another sheet of pasta.

Press the edges firmly to seal the ravioli.

Bring a large pot of salted water to a boil. Carefully add the ravioli to the water and cook for 3-4 minutes, or until the pasta is al dente and the egg yolk is cooked to your liking.

While the ravioli is cooking, make the sauce by melting the butter in a large skillet over medium heat. Add the sage leaves and cook until the butter begins to turn golden brown and the sage leaves are crispy, about 3-4 minutes. Add the chopped hazelnuts and cook for an additional minute.

Using a slotted spoon, remove the cooked ravioli from the water and add them directly to the skillet with the brown butter sauce. Gently toss to coat the ravioli with the sauce.

Serve the raviolo garnished with additional Parmesan cheese