Heat the grill to medium. Pulse the bread in a food processor or blender to make breadcrumbs. Tip onto a baking tray with the hazelnuts and sugar, and mix well. Grill for about 10 mins, stirring frequently until lightly toasted (don't let it burn). Set aside to cool.

In a bowl, whisk the egg whites until stiff, then whisk in the caster sugar, a little at a time, until you’ve got a glossy meringue. In a separate bowl, whip the cream to soft peaks, then fold it into the egg white mixture along with the toasted breadcrumbs.

Tip into a large container with an airtight lid and freeze for about 4 hrs (the whipped egg white and cream will give it stability, so it won’t need churning). Remove from the freezer 15-20 mins before you want to serve so it softens a little. Sandwich between cookies, if you like.