Melt the butter in the microwave or on the stovetop. Allow it to cool for 5 minutes before combining it with the powdered sugar.
⅔ cup (150 g) salted butter, melted and slightly cooled, ¼ cup (32 g) powdered sugar (icing sugar)
Add the melted chocolate. Make sure the chocolate has cooled slightly to avoid curdling the mixture.
⅔ cup (113 g)chocolate, melted and cooled chocolate
Fold in the flour with a spatula to form a soft chocolate dough.
1 ¾ cups (218 g) plain flour
Scoop the chocolate dough out in slightly heaping ½ teaspoon portions and drop them onto a baking tray lined with parchment paper.
Shape each portion into a ball.
Use a fork to lightly flatten each rolled-out chocolate dough. Each cookie should be at least 1 inch (2½ cm) round.
Bake for 10 to 12 minutes in a preheated oven of 356°F / 180°C (160°C fan) until the chocolate cookies are lightly browned. (See note 4)
The cookies will still be soft when you take them out of the oven but will crisp as they cool.