In a medium bowl, whisk the egg and add Nutella, mixing until well combined.

Add the flour and stir until the mixture comes together and there is no visible flour or egg streaks (I find using my hands easiest for this step). Add the white chocolate if using.

Form into 12 balls, cover and place in the fridge for at least 1 hour (or best overnight) – this helps intensify the flavours and prevents the cookies from spreading when baked).

When ready to bake, preheat oven to 175C (350F) and line a baking tray with baking paper. Place cold cookie dough balls on the baking tray and press them with a fork slightly. Bake for exactly 15 minutes*.

Leave to cool slightly on the tray for 10 minutes before transferring onto a wire rack.

These cookies can be stored in an airtight container and will keep for 3-4 days.