Chill the coconut milk. Place the can in the fridge overnight so the cream separates from the liquid.
Prep the chocolate. Add the chopped dark chocolate to a heat-safe bowl.
Warm a portion of coconut liquid. Open the can and scoop out the solid cream into a chilled mixing bowl. Pour about 1/4 cup of the remaining coconut liquid into a small saucepan and warm over low heat until steaming, not boiling.
Melt the chocolate. Pour the hot coconut liquid over the chocolate and let sit for 1 minute.
Stir until smooth and glossy. If a few pieces remain, set the bowl over a pan of gently simmering water and whisk until melted.
Whip the coconut cream. Using a hand whisk or electric mixer, whip the chilled coconut cream until light and slightly fluffy, 1–2 minutes.
Flavor it. Whisk in the maple syrup, vanilla, and a pinch of sea salt until smooth.
Combine. Gently fold the melted chocolate into the whipped coconut cream in two additions. Fold just until no streaks remain.
The mixture should be thick and silky.
Chill to set. Spoon into 4 small glasses or ramekins. Refrigerate for at least 1–2 hours, or until set and mousse-like.
Finish and serve. Top with berries, shaved chocolate, or toasted coconut. Serve cold.