A traditional cookie from Piedmont in Italy's North, these family favourites are known as biscotti di meliga. They're usually served with a glass of moscato or dolcetto and perhaps served with some creamy zabaione as an after dinner treat. But, like most biscotti, they also are great with a homemade espresso or tea. Traditionally, they are more commonly found in a ridged ring shape made by piping the dough through a star-shaped tip, but here I've rolled the dough and used a cookie cutter. —Emiko
Combine the flours and sugar in a bowl, add the chopped butter and process in a mixer or, if mixing by hand, rub into the dry ingredients until the mixture resembles breadcrumbs.
Add the yolks and lemon zest and mix until you form a smooth ball of dough. Rest the dough at least 30 minutes in the fridge (it can also be left overnight).
Roll the dough on a well floured surface until about 1/3 inch thick and cut out rounds with a cookie cutter (about 2 inches in diameter). Place on a baking sheet and bake at 350ºF for about 15 minutes or until just golden.