1. Place the butter and sugar in the bowl of an electric mixer with the paddle attachment in place. Beat on a medium-high speed until light and fluffy, then gradually beat in the egg until incorporated.

2. Sift the flour, baking powder, cocoa powder, mixed spice and salt into a bowl, then add to the butter mixture. Mix on a low speed for about 15 seconds, add the chocolate chips and banana, and continue to mix until combined. Cover the bowl with clingfilm and transfer to the fridge for at least 1 hour (and up to 2 days) to firm up.

3. When ready to bake, preheat oven to 180C (170C fan-forced) and line a baking tray with baking paper.

4. Place the hazelnut in a medium bowl, and the sifted icing sugar in a separate bowl. Remove the dough from the fridge and use an ice-cream scoop (or your hands) to form balls of about 3cm diameter, roughly 20g each. Roll the balls in the hazelnut so that they are completely coated and press the nuts in so that they stick. Then roll balls in the sugar so they are thickly coated all over. Place on the lined baking tray spaced 2cm to 3cm apart, then use your palm to flatten the cookies to 1cm thick.

5. Bake for 10 minutes if you like a slightly gooey centre, and 12 minutes for a crunchier cookie. Remove from oven and cool on the tray for 10 minutes before gently transferring to a wire rack or plate. The cookies are best eaten on the day they are made, although will keep for up to 2 days.

Tip: Once the uncooked dough balls have been coated in the hazelnut and icing sugar, they can be kept in the fridge for up to 2 days, or frozen for up to 3 months. You can bake them from frozen, just add a minute or two to the baking time.