Line your tray. Take a large baking tray and line it with parchment paper. You want the paper to sit flat—no folds or creases—so the cookies have an even base. Set the tray aside for now.

Melt the wet ingredients. Place the caster sugar, milk, and butter into your heavy-bottomed saucepan. Set it over a medium heat and stir gently as the butter melts and the sugar dissolves. You’ll know it’s ready when the mixture is smooth, glossy, and just beginning to steam—don’t let it boil vigorously.

Bring to a rolling boil. Once the sugar has fully dissolved (test by rubbing a little between your fingertips—it should feel silky, not gritty), increase the heat slightly and let the mixture come to a full, rolling boil. Let it bubble away for exactly 1 minute, stirring constantly. The liquid will darken slightly and smell deeply caramelised.

Remove from heat and add peanut butter. Take the pan off the heat immediately. Add the peanut butter and the sifted cocoa powder. Stir vigorously until everything is fully combined. You’re looking for a thick, fudgy sauce that coats the back of your spoon. The smell at this stage is utterly intoxicating—rich, chocolatey, and nutty.

Add the oats and vanilla. Tip in the rolled oats, desiccated coconut (if using), and the vanilla extract. Stir with real determination—the mixture will be stiff and sticky. You want every oat to be completely coated in the chocolate-peanut butter sauce. The texture should look like a very clumpy, slightly wet granola.

Scoop and shape. Using a tablespoon or a small cookie scoop, drop heaped spoonfuls of the mixture onto your prepared tray, spacing them about 2cm apart. If you like perfectly round cookies, lightly wet your hands and press each mound into a neat disc. The mixture will feel warm and pliable in your hands.

Chill until firm. Place the tray in the refrigerator for at least 30 minutes. The cookies will set into firm, chewy rounds. They should feel solid to the touch but still give slightly when you press them—that’s the perfect texture.

Transfer to a cooling rack. Once set, carefully lift each cookie from the parchment paper and place it on a wire cooling rack. This stops any condensation forming on the bottom. Let them sit at room temperature for 5 minutes before serving—the texture will soften just a little, making them perfectly chewy.