Sauté the onion in the extra virgin olive oil for a minute.

Add the shredded radicchio and mix well.

Season with salt to taste, mix and cook, covered, until tender and until the liquid has evaporated. Let it cool down.

Mash the gorgonzola with a fork in a bowl.

When cold, add the cooked radicchio to the gorgonzola and mix well until combined and creamy.

Add the finely grated Parmigiano Reggiano, mix and adjust the seasoning if required. Keep aside.

Make the Tortelloni following my tutorial on How to make Tortelloni.

Keep them aside.

Put the butter and walnuts in a frying pan and sauté them until the butter melts.

Put the fire off and keep aside.

Cook the Tortelloni following the steps on “How to cook pasta al dente”. Only in this case you will not have a pre set cooking time. This will vary on the thickness of your pasta (it should take approximately a couple of minutes to cook if you have just made the pasta. If a number of hours have passed since you made the pasta then it would be slightly dry and could take between 10 to 12 minutes to cook). So, the best solution is to taste it! Remember, to check the joint, where your pasta is thicker. It does have to remain firm to be al dente.

When the pasta is cooked, drain it and put it in the pan with the walnut butter sauce. Mix well on low fire for a minute.

Serve hot with some thinly grated Parmigiano Reggiano on the top.