In a large bowl, beat the butter and sugar until pale and creamy.  Add the egg and vanilla and continue beating until the sugar grains are superfine.  Sift in the flour and cornstarch, and mix with a wooden spoon until well combined.

Divide the mixture evenly into three bowls.  In one, add the cocoa powder and mix well.  In another, add the food colouring and strawberry essence.  Add a little at a time – you can always add more but never take from the mix.  Use your hands to mould the dough into a ball then flatten slightly, wrap in cling film and place in the fridge for 20 minutes.

Preheat the oven to 180ᵒC.

Remove the dough from the fridge and roll out between two pieces of baking paper until 5 mm thick.  Use a medium shape heart cookie cutter to cut out hearts in the dough.  Using a smaller cookie cutter, cut the centre of the heart with a smaller heart.  Place the smaller hearts to the side and the larger ones on a baking tray.  Continue with the other two dough’s.  With all the large hearts cut out, place the smaller hearts in the centre, mixing up the colours as you go.

Place in the oven and bake for 10 – 12 minutes or until set.  Be careful not to overcook as they will become too dry.

Allow to cool on a wire rack then dust with icing sugar.