Preheat and prepare: Heat your oven to 180°C (160°C fan). Line two baking trays with parchment paper. The paper should lie flat without curling at the edges — that's your cue it's ready.

Mix the dry base: In a large bowl, whisk together the plain flour, cocoa powder, baking powder and salt. You'll see the cocoa powder disperse evenly, turning the mixture a deep, uniform brown. Set this aside.

Combine wet ingredients: In the same bowl (yes, the one you just used — less washing up), pour in the melted butter and caster sugar. Stir vigorously with a wooden spoon until the mixture looks glossy and feels smooth, like a thick paste. Add the eggs one at a time, beating well after each addition. The batter will become looser and shinier. Stir in the vanilla extract.

Bring it together: Tip the dry ingredients back into the wet mixture. Fold gently with a spatula until just combined — you should see no streaks of flour, but stop as soon as it comes together. The dough will be soft and slightly sticky to the touch. Fold in the dark chocolate chips until they are evenly distributed.

Chill briefly (optional but recommended): Cover the bowl and pop it in the fridge for 10 minutes. This firms the dough slightly, making it easier to roll. If you are in a rush, you can skip this step, but the cookies will spread a little more.

Shape and coat: Place the icing sugar in a shallow bowl. Using a tablespoon or a small cookie scoop, portion out balls of dough about the size of a walnut. Roll each ball between your palms until smooth, then drop it into the icing sugar. Toss to coat generously — the more sugar, the better the crinkle effect. Place the coated balls on the prepared baking trays, leaving about 5cm of space between each one. You want them to have room to spread without merging.

Bake to perfection: Bake for 10 to 12 minutes. At the 8-minute mark, check through the oven door: the cookies should have spread and the tops will be covered in cracks, revealing the dark chocolate dough beneath. The edges will look set, but the centres will still appear slightly soft and puffy. That is exactly what you want — they will continue to set as they cool.

Cool completely: Remove the tray from the oven and let the cookies rest on the hot tray for 5 minutes. They will be very fragile when hot. After 5 minutes, transfer them to a wire cooling rack using a thin spatula. You will hear a slight sizzle as they hit the rack — that's the sound of them settling. Let them cool completely before serving. The texture should be crisp at the edges and soft, almost fudgy, in the centre.