A rainy day project for all the family! The chequerboard is made in 4 quarter sections, which are joined after baking to make a 40 x 40cm playing board with 100 squares (50 lemon, 50 chocolate). It’s piped with icing snakes and ladders.
Heat the oven to 190°C/170°C/375°F/Gas 5.
Make the lemon dough. Put the flour, semolina, ground almonds, sugar and lemon zest into a food-processor bowl and pulse to combine. Add the butter and blitz until the mixture resembles breadcrumbs.
Add the egg, lemon extract and juice, yuzu juice, and the edible bergamot oil (if using). Blitz again until almost combined. Carefully tip the mixture into a large bowl and knead to make a firm, but not crumbly dough.
Turn out the dough onto a lightly floured worktop. Roll into a large 40 x 20cm rectangle and 5mm thick. Using the ruler and a large knife, cut away the edges to make a very neat rectangle measuring exactly 38 x 19cm. Divide the long side into 10 strips, then cut across the short side in 5 strips to make 50 squares of 3.8cm. Cover lightly with cling film and set aside. Save the trimmings.
To make the chocolate dough, put the chocolate chips, flour, almonds, cocoa powder and sugar into the food-processor bowl and pulse to combine and make the chocolate chips smaller. Add the butter and blitz to make crumbs, then add the eggs and blitz again until the mixture just begins to come together. Tip into a large bowl and knead to bring the dough together.
Repeat step 4 for the chocolate dough, then cut the saved chocolate trimmings into strips measuring 1cm wide and 20cm long.
Assemble the 4 quarters that make up the board. Place each square of parchment-lined foil on a baking sheet. Place the lemon and chocolate squares alternately in 5 rows of 5 on each square of parchment-lined foil. Edge 2 adjoining sides of each quarter with the chocolate dough strips, so that when the 4 quarters are assembled, the board has a complete edging.
Roll and cut the lemon dough trimmings into playing pieces and dice, then bake alongside the squares for 15–18 minutes – the squares will take a little longer, about 18–22 minutes in total, or until they just start to turn golden and the biscuits are firm. Remove from the oven and leave to cool on the baking sheets.
Meanwhile, make the royal icing. Mix the royal icing sugar with 1 1/2 tablespoons of water to make a smooth, thick, pipeable icing. Transfer the icing to smaller bowls (one for every colour you want to use). Add a little colouring gel to each bowl, then transfer each to a separate small piping bag, fitted with a fine writing nozzle (if using).
Carefully assemble the board on a very large cutting board or thick piece of card, gently pressing the 4 quarters together. If the biscuits don’t quite fit neatly, very gently trim them so the chocolate edging runs neatly around the outer edge of the board.
To decorate, pipe snakes and ladders on the board – adding eyes, and stripes or spots to the snakes. Leave to set.