Start the base: Place your saucepan over a medium heat and add the milk. Watch for the first tiny bubbles to appear around the edge of the pan — this takes about 2 minutes. You want it steaming, not boiling. When you see that faint shimmer on the surface, you’re ready.

Whisk in the dry ingredients: Drop the heat to low. Add the cocoa powder, sugar, and salt directly to the warm milk. Whisk vigorously in a figure-eight motion. You’ll see the mixture turn a deep, matte brown. Keep going until no dry specks remain — about 30 seconds of steady whisking.

Add the butter and chocolate: Tumble in the diced butter and chopped dark chocolate. Stir gently with a wooden spoon or spatula. Within a minute, you’ll see the butter melt into glossy yellow ribbons, and the chocolate will darken the liquid. The smell shifts from plain milk to a deep, toasty cocoa aroma.

Simmer gently: Continue stirring for 2 to 3 minutes. You’ll feel the mixture thicken slightly against your spoon — it should coat the back of the spoon lightly. Small bubbles will break the surface, but you don’t want a full boil. The colour will become a rich, velvety brown, like melted dark caramel.

Finish with vanilla: Pull the pan off the heat. Stir in the vanilla extract. You’ll notice the scent brighten immediately — that warm, sweet note cuts through the deep chocolate. Give it one last stir.

Serve immediately: Pour into your favourite mugs. If you’re making the extra-creamy version, whisk the double cream until it’s just thick enough to hold a soft ribbon, then spoon it on top. The surface should look glossy and smooth, with no skin forming.