Chocolate mousse fills most of this tart, but underneath it, there’s a layer of chocolate and blackberries blended together. If you prefer raspberries to blackberries, they work well too.
Combine the milk and 2tablespoons of the cream in a saucepan, and bring just to a boil. Pour the hot milk all at once over the chocolate. Let sit for 1 minute, then whisk until smooth. Let cool to room temperature.