Roughly chop the Fontina, whisk the egg yolks with a couple of tablespoons of milk, blend the flour into the remaining milk and add the fontina to the mixture. Transfer the mixture over the heat and keep whisking vigorously with a metal whisk.

As soon as the mixture starts to become more solid, amalgamate everything with the egg mixture, and, cook for ten minutes, stirring continuously. Season with salt, if you want you can add a knob of butter, and leave to rest.

Finely chop the radicchio and add it to the cheese mixture. Heat up the fondue and fill the vol au vents finishing with some freshly-grated black truffle on top.

Food History

Radicchio can be found throughout Italy. There are many types of this bitter, leafy vegetable, but the most famous is probably the late-season radicchio tardivo di Treviso.
Italians began cultivating his variety, a quite labor-intensive process, in the middle of the 1500s. After the harvest, which normally takes place around November, the “tardivo” undergoes a process called imbianchimento, literally “whitening”, which involves placing the plants in baths of water for about twenty days so that the leaves become crisp and less bitter in flavor.
Or more specifically, the outer leaves of the plants are removed and then they are places in large cement basins where they can form new, crisper leaves. Then the radicchio is left to ripen in sand, and then cleaned and trimmed before they are sold at markets across Italy.

Other suggested recipes

• Crepes with Treviso radicchio
• Trevisio Radicchio with Red Wine and Pears
• Radicchio with Speck