Butter 2 souffle cups and sprinkle bottom and sides with sugar. Place cups on a baking sheet and chill while preparing the soufflés. Melt chopped chocolate with milk, coffee liquor, instant espresso, cornstarch, ½ teaspoon sugar and cinnamon over medium heat, whisking until mixture is smooth.
Using an electric mixer, beat egg white with cream of tartar and salt on high speed until soft peaks form. Gradually add remaining 1-1/2 teaspoons sugar; continue beating until stiff peaks form (whites stand up when beaters are lifted from bowl). Using a whisk, blend whites into chocolate mixture until there are no streaks. Fill prepared cups with batter. Bake on the baking sheet until souffles puff, about 20 minutes. Test for doneness by inserting a skewer into the center of a souffle-- souffle is done when skewer comes out clean or slightly moist .
To serve: Cut a slit in the top of each soufflé and pour the Dulce de Leche Sauce. Garnish with whipped cream and chopped nuts.
Dulce de Leche Sauce:
Boil cream, brown sugar, salt and cinnamon whisking constantly. Reduce liquid to half and remove from the heat; add vanilla.