Begin by chopping cold unsalted butter into small pieces and placing them in a mixing bowl. Use an electric mixer to beat the butter until slightly softened, about 1-2 minutes. Gradually blend in the light brown and white sugars until just combined.

In a separate bowl, whisk together the self-raising flour, plain flour, salt, and baking powder until fully combined. Gradually fold the dry ingredients into the butter mixture with a spatula, mixing gently until a thick dough forms without overworking it.

Stir in the chocolate chips by hand using a spatula, ensuring they are evenly distributed throughout the dough.

Divide the cookie dough into equal portions of about 120g each, rolling them into rustic balls with your hands. Place these dough balls onto a lined baking tray and freeze for a minimum of 90 minutes.

Preheat your oven to 180°C (fan) while the dough is chilling. Arrange the frozen dough balls on the tray and bake for 15 minutes, watching for golden color while keeping centers soft.

Allow the cookies to cool on the baking tray for about 5 minutes before transferring them to a wire rack to cool completely or enjoy them warm.