Chop the chocolate. Finely chop the dark chocolate so it melts quickly and evenly.
Small pieces prevent scorching and lumps.
Warm the dairy. In a medium saucepan, add the milk and cream. Heat over medium-low until it’s steaming and small bubbles form at the edges. Do not let it boil.
Whisk in cocoa and sugar. Sprinkle in the cocoa powder and 2 tablespoons sugar.
Whisk steadily to dissolve and smooth out any clumps. Taste and add more sugar if needed.
Add the chocolate. Remove the pan from heat, add the chopped chocolate, and let it sit for 30 seconds. Whisk until fully melted and glossy.
Season and thicken. Stir in the vanilla and a pinch of salt.
Return the pan to low heat and whisk gently for 2–4 minutes. The mixture will thicken slightly and coat the back of a spoon.
Adjust consistency. For thicker Parisian style, simmer on low another 2–3 minutes, whisking often. For lighter texture, add a splash of milk to loosen.
Serve warm. Pour into small cups—this is rich, so smaller servings feel just right.
Top with a dollop of softly whipped cream or a few chocolate shavings if you like.