Apricot and Pistachio Tiffin

To make the marshmallows, put the sheets of gelatine into a bowl, cover with cold water and leave to soak and soften until needed. Combine the sugar, water and glucose in a small pan over low heat and dissolve the sugar, stirring frequently, without letting the mixture boil. Meanwhile, put the egg white into a large, very clean bowl and whisk with an electric mixer until it will form stiff peaks.

Bring the sugar syrup to the boil, then boil rapidly, without stirring, until it reaches 127°C on a sugar thermometer. Pour the hot syrup on to the whisked egg white in a thin, steady stream while whisking constantly at high speed – the mixture will turn quite liquid. Lift the gelatine sheets out of the water and gently squeeze them to remove excess water, then add to the meringue along with the vanilla and whisk for 5–7 minutes until the mixture cools and thickens enough to hold a shape (like a soft peak).

Heavily dust an oiled baking sheet or large tin with icing sugar, then spoon half the marshmallow mixture into the centre. Using a palette knife dipped in cold water, gently spread the marshmallow out to a rectangle 1cm thick. Scatter the apricots evenly over it, then spoon the rest of marshmallow on top and spread it in a very smooth, even layer. Dust with more icing sugar. Place in the fridge to chill for about 1 hour until firm.

Cut the marshmallow into 2cm cubes using a pizza wheel-cutter or large knife. Toss the cubes in icing sugar to prevent them from sticking together, then set aside in a cool spot until needed.

To make the digestives, heat your oven to 180°C/350°F/gas 4 and line 2 baking sheets with baking paper. Grind the nuts in a food processor to a fairly coarse powder – don’t let the mixture turn sticky. Using a wooden spoon or electric mixer, cream the butter with the sugar in a mixing bowl until soft and fluffy. Sift the flour, salt and baking powder into the bowl. Add the oatmeal and ground nuts and mix everything together – first with a wooden spoon or plastic spatula, then with your hands.

Turn the dough on to the worktop and gently knead with your hands until it holds together (if the mixture feels very oily wrap it in clingfilm and chill for about 20 minutes until firm). Divide the dough in half and roll out each portion on the very lightly floured worktop to 4mm thick. Cut into squares about 5cm (they are going to be broken up, so they don’t have to be neat) and arrange slightly apart on the lined baking sheets. Place in the heated oven and bake for about 12 minutes until golden brown. Allow the digestives to cool on the sheets for a few minutes to firm up, then transfer to a wire rack and leave until cold.

To make the chocolate mixture measure the syrup, butter and chocolate into a large pan (preferably non-stick). Set over very low heat and stir gently until melted and smooth. Remove from the heat. Pour 250g of the mixture into a small heatproof jug or bowl and set aside for the topping. Leave the rest in the pan until it has cooled to room temperature – if the chocolate is warm it will melt the marshmallows.

Set aside 5 digestive biscuits for the decoration and roughly break the remainder into the cooled chocolate mixture. Add half the pistachios, half the apricots and the salt. Mix thoroughly, then gently stir in half the marshmallow cubes. Tip into the prepared brownie tin and spread evenly, then compress the mixture with the back of a spoon or spatula, making sure the surface is flat. Pour over the reserved chocolate mixture (gently warmed if necessary) to give a smooth, even covering. Scatter the rest of the pistachios and apricots over the surface. Cover the top of the tin with clingfilm, then chill for about 4 hours until firm and set.

Carefully turn out the tiffin and cut into squares. Decorate with the remaining marshmallow cubes and reserved digestives, broken up.

Apricot and Pistachio Tiffin first made by Glenn Cosby on BBC2’s Great British Bake Off 2013.