When you come to dipping the shortbread, start with 100g dark chocolate. You’ll only use about 50g of this but if you start with just 50g you won’t have the depth of chocolate needed for a good dip. To melt, I blast the chocolate for one minute in the microwave and then additional 10 second blasts until the chocolate is glossy and completely melted. I use a small bowl or even a mug, so that the melted chocolate has sufficient depth. Alternatively, use a small saucepan with an inch of simmering water heating a glass bowl with the chocolate in it instead.
Greaseproof or baking paper
Find it online: https://www.type1kitchen.com/starry-chocolate-shortbread/