Pre-heat oven to 180°C (360°F) with fan. In two separate bowls add equal quantities of 120g flour (1 cup) and 10g cornstarch (1 ½ tbsp). Give both a good whisk to combine the ingredients in each separate bowl.
Separately, combine the softened (room temp) butter and sugar. Beat with a hand mixer until light and airy.
Beat in the melted chocolate, egg, lemon zest and lemon extract.
Divide the butter mixture into two equal parts in separate bowls, each weighing approximately 140g. If using imperial units, this would be around ½ cup + 4 teaspoon of mixture.
Mix in your preferred colour in each buttery mixture, using either powder or gel food colouring. Combine well to get a uniform colour.
Add the corresponding dry ingredients over each separate butter mixture. This will give you two identical weight doughs, in two different colours. Mix the wet and dry ingredients with a spatula or wooden spoon. Use your hands to fully incorporate into a smooth dough. Do not add any additional flour, the dough is supposed to be a little on the 'wet' side.
Shape each dough into a thin roll, then divide the doughs into 12 equal parts. Cover the dough with cling film to prevent it from drying out.
Take one small part of each colour dough, then roll it out into a thin strip with your palms. Twist the two tones around each other to make a braid, then press them with your fingers to stick together. Now roll out the braid to make into a thin strip.
Cut off ¼ of the strip and reserve. Divide the remaining strip of dough in half, then shape each half into a bow loop. Connect the two loops together and gently press them together in the middle. Take the reserved strip of dough and divide it in half. Add each half as ribbons coming from the bow. Optional: add a small circle of dough in the middle of the bow to hide the seam.
Place the bows on a baking sheet and bake for 8 minutes. Once baked, let the cookies cool down on the tray until they're fully cooled and hardened.
Notes
I recommend using a kitchen scale in grams for more accuracy. The cups used for the conversion are standard US customary cups (1 cup flour = 136g). There are many different types of cups across the globe, which is why I strongly recommend using grams instead.
The cookie dough can also be made in one piece, then divided into two equal parts and coloured separately. However, this method will not result in perfectly blended colours and you risk over-kneading the dough.
Please do not eat the raw cookie dough, unless you are using pasteurised eggs.