Preheat the oven to 180C/350F/Gas 4, and line a baking tray with parchment paper, or a silicone mat. Set aside.
Whisk together the flour, baking powder, baking soda, cornflour, salt, and 2 tablespoons of instant coffee granules. Set aside.
Whisk together the melted butter and sugars until combined. Add the egg and mix until combined.
Dissolve the remaining 2 tablespoons of instant coffee granules in 1 tablespoon of hot water, then add to the wet ingredients, and mix until combined.
Add the dry ingredients, and mix until just combined. Fold in the chocolate chips.
Roll the dough into 1.5oz balls, and place onto the prepared baking tray. Bake for 10 - 12 minutes.
Allow to cool on the baking tray for 5 - 10 minutes before transferring to a wire rack to cool completely.
For the Coffee Drizzle
Whisk together the icing sugar, coffee granules, and water until smooth and combined. Drizzle over the cooled cookies.
Video
Notes
*Use a coffee you absolutely love to drink! The taste is everything in this recipe. If you'd like a weaker coffee taste, skip the 2 tablespoons of coffee in the dry ingredients.Cookies stay fresh, kept in an airtight container, at room temperature for up to 1 week. Cookie dough balls can be kept in the fridge for up to 5 days, or frozen for up to 3 months. Bake from frozen for an extra minute.