Place dark chocolate in a medium heatproof bowl and set aside.
In a medium saucepan, combine maple sugar, cocoa powder and corn starch until evenly blended and smooth. Slowly pour in cream while whisking well. Whisk in egg yolks and maple syrup, and then whisk in milk until combined. Bring the mixture to a gentle boil over medium heat while whisking constantly. Once boiling, reduce heat slightly and boil for 1 more minute while whisking.
Remove pan from heat and pour the mixture through a sieve over the chocolate in the bowl. Add vanilla and salt and whisk until chocolate is melted and smooth. Cover with plastic wrap directly on the surface and let cool at room temperature for about 20 minutes before refrigerating for at least 4 hours or until set.
Once chilled and set, stir the pudding with a whisk until smooth and silky before spooning into serving cups. Sprinkle brown sugar over top just before serving. Makes about 6 servings.
For a thick-set pudding, spoon the hot mixture directly into your serving cups, cover with plastic wrap and refrigerate until set.