Preheat oven to 180°C (160°C fan) mark 4. Put all the biscuit ingredients into a food processor and pulse until the mixture clumps together. Tip the dough on to a work surface and bring together.
Step 2
Roll out the dough on a sheet of baking parchment, trying to keep it rectangular and dusting your rolling pin with flour as needed, then trim to a 23cm x 30.5cm (9in x 12in) rectangle. Cut the rectangle lengthways into 3 even strips, keeping strips together, then cut across them at 2.5cm (1in) intervals, keeping the rectangles together. If you like, use the end of a skewer to mark the long edges of each biscuit with five dots to resemble a traditional Bourbon. Chill for 30min.
Step 3
Bake for 25min, then carefully remove the tray from the oven and cut through the marks to make sure biscuits are separated. Leave to cool completely.
Step 4
To make the filling, put the butter into a large bowl and sift in the icing sugar and cocoa powder. Mix until combined (don't be tempted to add any liquid - the icing should be thick).
Step 5
Sandwich the cooled biscuits together with the chocolate filling, using a piping bag if you want a neater finish.
A crack team of highly skilled food content producers, the GH Kitchen Team are Good Housekeeping’s resident recipe developers and all-round food obsessives. GH Kitchen Director Sarah Akhurstis our resident hosting pro and loves nothing more than putting on a foodie feast for friends. Senior Cookery Writer Alice Shields is a former pastry chef and baking fanatic who loves making bread and would have peanut butter with everything if she could. Lover of all things savoury, Senior Cookery Writer Grace Evans can be found eating nocellara olives at every opportunity, and will take the cheeseboard over dessert any time. With a wealth of professional kitchen experience between them, they’re dedicated to ensuring every Good Housekeeping recipe is the best it can be, so you can trust they’ll work every single time.
