The only thing better than chestnut purée is a chocolate, marshmallow and chestnut purée combo, all together in one indulgent biscuit butty. These will keep for a good few weeks in a biscuit tin, if you can resist, that is. 

Ingredients - makes 16-18

  • 200g dark chocolate, roughly chopped
  • 20g unsalted butter
  • 2 eggs
  • 100g dark muscovado sugar 70g light muscovado sugar 80g plain flour
  • 1/2 tsp baking powder
  • 1/4 tsp salt

For the Marshmallow Filling

  • 3 gelatine leaves
  • 200g golden caster sugar
  • 75g golden syrup
  • 100ml water
  • 1 x 250g can vanilla chestnut purée, I use the brand Clément Faugier

Essential Equipment

  • Sugar or digital food thermometer
  • At least 2 baking sheets, lined with baking paper
  • Freestanding electric mixer and whisk attachment, or handheld electric whisk
  • Disposable piping bag, with a little of the end snipped off 

Preheat the oven to 200°C/180°C fan/Gas 6. Place the chocolate and butter into a heatproof bowl over a pan of barely simmering water, and allow to melt slowly. Meanwhile, whisk together the eggs and dark sugars until well combined. Beat the melted chocolate and butter into the sugar and egg, then sift over the flour, baking powder and salt, and beat to a smooth, glossy batter. Allow to cool and thicken slightly.

Scoop heaped teaspoons of the batter on to the lined baking sheets, well apart as they will spread in the oven. You should end up with about 36 blobs, so you might need to bake in batches. Bake for 10–12 minutes, or until well risen, shiny, and cracked over the surface. Allow to cool, out of the oven, on the baking sheet, before removing with a palette knife.

To make the filling, submerge the gelatine leaves, one by one, in a bowl of cold water. Place the sugar, syrup and water in a medium saucepan and heat on high until it reaches 118°C. Quickly squeeze excess moisture from the gelatine, add to the pan and swirl to dissolve. Pour this into the mixer and whisk on full speed until very thick, sticky and only slightly warm: about 5 minutes (this will take about 10 minutes using a handheld electric whisk).

Turn half the cookies over so they are bottom up. Spoon a teaspoon of chestnut purée on to each. Pile the marshmallow into the piping bag, then pipe a ring of marshmallow around the chestnut purée. Sandwich the remaining cookies on top.