To prepare the filling for the kariokes, pour in a pot the water and sugar and bring to the boil. Let it boil for a few minutes, until the sugar has dissolved.

Remove the pot from the stove and add the butter, the chocolate (cut in small pieces), the orange zest and the lemon juice; blend until the chocolate has melted and the ingredients combine.

Pour the mixture in a bowl and mix in the powdered biscuits and chopped walnuts. Blend, until the ingredients combine.

On a working surface, line some plastic wrap and pour in 1/3 of the mixture. Form the mix into a roll, wrap it up and put it in the fridge overnight. Repeat the same with rest of the mixture, forming 3 rolls, about 17cm long and 3-4 cm thick. Leave in the fridge overnight.

A little bit before you take the rolls out of the fridge, start making the coating. To melt the chocolate it is best to use a bain-marie (or double boiler), a piece of equipment used to heat the chocolate gently and gradually to fixed temperatures so that it doesn't burn.

Take the rolls out of the fridge, unwrap the plastic wrap and slice them in equal slices, about 1cm thick. Dip each piece in the chocolate, using a fork and then place on a baking tray, lined with parchment paper; repeat with all the pieces.

When done, let the kariokes to cool down, at room temperature (not in the fridge), until the chocolate thickens. Enjoy!