01 - Place the chopped dark chocolate in a heatproof bowl set over a saucepan of gently simmering water (double boiler). Stir continuously until the chocolate is fully melted and smooth, then remove from heat and allow to cool slightly.
02 - In a food processor or high-speed blender, combine the peeled and pitted avocados, the slightly cooled melted dark chocolate, pure maple syrup, vanilla extract, fine sea salt, unsweetened cocoa powder, and almond milk. Blend until the mixture is silky smooth and thoroughly combined, pausing as needed to scrape down the sides of the bowl or blender.
03 - Taste the prepared mousse. Adjust the sweetness or chocolate intensity to your preference by incorporating additional maple syrup or cocoa powder if desired. Blend again briefly to incorporate any additions.
04 - Evenly spoon the finished mousse into individual serving glasses or ramekins. Cover each portion and refrigerate for a minimum of 1 hour, or until the mousse is firm and well chilled.
05 - Just prior to serving, lightly sprinkle each chilled mousse with flaky sea salt. For an optional decorative touch and added flavor, garnish with fresh berries or cocoa nibs.