Line a large tray or two with baking paper.
Mix the butter and sugar together until smooth. Then stir in the peppermint extract and the food colouring.
Add the flour. Mix well, then use your hands to press everything together into a ball of dough. Remember, shortbread dough is supposed to be quite crumbly.
Pour the chocolate chips into the bowl and press them into the dough.
Roll the dough onto a lightly floured surface until it's around ¼-inch thick. Cut out 2.5-inch circles, re-rolling scrap pieces together until all of the dough is used up.
Place the biscuits onto your lined tray(s) then pop them in the fridge for 30 minutes. This will help them to hold their shape in the oven.
In the meantime, preheat your oven to 180℃/350℉ (or 160℃/320℉ if you're using fan/convection setting).
Bake your biscuits for 12-15 minutes until they're firm to the touch around the edges. If you used a smaller cookie cutter, they'll bake faster, so keep an eye on them.
Sprinkle some extra sugar on top of the biscuits while they're still warm. Let them cool on the tray then enjoy!