1.Grease and line a 12″x 9″ tin with cling film. Scatter half of the digestive biscuit crumb in an even layer at the bottom of the tin, making sure it is covered well.

2. Scatter the chocolate chips over the biscuit crumb base and set aside. In the bowl for a stand mixer, add the cold water and the gelatine. Soak until the gelatine has softened.

3. In a large saucepan, add the sugar and syrup and add enough water to just cover the sugar. Slowly heat until the sugar is dissolved, then increase the heat until on a sugar thermometer reads 130C. Run the stand mixer with the water and gelatine to break up slightly. On a slow to medium speed, add the hot syrup to the gelatine mixture, pour the mixture to the side than on the whisk or you’ll get sugar shards. Once added all the syrup, increase the speed to high and beat the mixture until it has cooled and ballooned in size and a pale fluffy mixture. Beat in the vanilla extract. The mixture will be ready when looks like a bubble gum texture and stiff peaks.

4. This is where it gets fun! It’s going to be one big sticky mess but totally worth it. Spoon into the prepared tin, careful to not stir in the crumbs into the mixture as you want a nice clear layer of the crumb and chocolate. Level out the mixture and scatter over the remaining half of the biscuit crumbs to coat the surface of the marshmallow. Leave uncovered overnight to set further.

5. Using a lightly greased sharp knife, neatly cut the marshmallows into squares. Enjoy on top of hot chocolates or even toasted for the ultimate S’mores!