Christmas crackle cookies

Whisk the eggs with the sugar and vanilla until thickened. Mix in the melted butter.

Sift the flour, salt and cocoa powder into a mixing bowl, add the chocolate chips and make a well in the centre. Gradually pour the egg mixture into the middle, incorporating the wet ingredients with the dry as you go. Cover the bowl and chill for 1 hour.

Preheat the oven to 180ºC, gas mark 4. Line a baking tray with baking parchment. Put the icing sugar in a shallow bowl. Divide the cookie dough into walnut-sized pieces and roll into balls. Drop each into the icing sugar and coat generously. Do not tap off the excess.

Put as many balls as you can on the prepared baking tray, making sure to give each one a little space to spread. Bake for 10-12 minutes, until spread slightly and crackled on top. Remove, transfer to a wire rack and leave to cool while you repeat the process with the remaining dough. Leave to cool completely. They will keep for 4 days in an airtight container.