Makes: approx. 18 shortbreads
150 grams plain flour
75 grams grated parmesan
100 grams soft unsalted butter
1 large egg yolk
large handful of finely chopped rosemary
Mix all the ingredients together – using bowl and spoon, electric mixer or food processor as wished – until a golden dough begins to form a clump.
Turn it out onto a surface and knead for about 30 seconds until smooth, then divide into two.
Take the first half and, using your hands, roll it into a cylinder, as uniform as possible without stressing over it, about 3cm / 1¼ inches in diameter. Make sure the ends are flat, too, so that the cylinder resembles a roll of coins. Now roll this up in a piece of clingfilm, twisting the clingfilm at the ends, like a Christmas cracker, and put the roll in the fridge, then proceed in the same way with the remaining half of the dough.
Preheat the oven to 180°C/gas mark 4/350ºF while the wrapped cylinders of dough rest in the fridge for about 45 minutes, by which time you should be able to cut them into thick slices easily: aim for about 1cm / ½ inch thick.
Arrange on a baking sheet lined with baking parchment, and put in the oven for 15–20 minutes, when they should be just beginning to turn a pale gold at the edges.
Remove from the oven, then leave to cool, before eating!