Bring a large pot of well salted water to the boil.
While the water is boiling place a separate pan on the stove and add 100ml of crème fraîche and bring it to just under a boil.
Add 100g of freshly grated Parmigiano Reggiano, a small pinch of finely grated nutmeg and pinch of black pepper. Place 1 egg yolk in a bowl and whisk in the hot cream. In a sauté pan put 2 tbsp butter and finely sliced leaves of 2 heads of radicchio for 5 minutes.
Cook tortelloni for 2 minutes, then drain delicately with a skimmer and place in the sauté pan.
Simmer gently over a low heat, tossing gently to coat the pasta.
Divide the tortelloni among plates and spoon a little of the warm cream on top.
CURATED BY SKYE GYNGELL