Melt the butter in a bowl in the microwave - it's best to do this in short, 10-15 second intervals as you want it just melted, not bubbling hot!

Add the melted butter and caster sugar to a large mixing bowl and beat with an electric whisk (or wooden spoon) until combined. Add the egg and beat again until it combines and forms a runny batter.

In a separate bowl, add the gluten free flour and baking powder and stir to mix it all together. Sift the flour mix into the butter/sugar mixture. Bring the mixture together using a wooden spoon. Once the mixture starts to come together, add the chocolate chips - I like to reserve a small handful of these to press into the top of the cookies before baking!

Use your hands to bring the dough together, making sure the chocolate chips are mixed well throughout. It should form a thick, sticky dough. Once it's completely mixed together (and there is no loose flour left in the bowl) wrap the dough in clingfilm and refrigerate for an hour.

Once the hour is nearly up, preheat the oven to 180'C / Fan 170'C / Gas Mark 4. Line two baking trays with baking paper. Take the cookie dough from the fridge and roll it into balls around the size of a golf ball. Flatten the balls onto the baking tray, making sure there is around 3cm between them in case of any spreading. Press any extra chocolate chips into the top of the cookies.

Bake the cookies in the oven for 15-18 minutes. You want them to appear a little crackled on top. Once baked, carefully remove the cookies from the oven and allow them to cool on the tray for 15-20 minutes before transferring to a baking tray to cool completely.