Lightly grease as many 4 oz soufflé cups as needed.
Sprinkle a small amount of sugar into each cup and rotate to evenly coat
the insides with the sugar. Discard any excess sugar.
Combine ¾ cup of sugar, cocoa, flour, cornstarch, and salt in a
saucepan. Using a wire whisk, stir until well-blended. Stir in the milk and
whisk until smooth.
Cook over medium-high heat, stirring constantly, until thickened. Remove
mixture from heat.
Separately whisk together egg yolks, vanilla, and orange liqueur; blend
mixture into chocolate.
Combine the egg whites and ¼ cup of sugar; beat until soft peaks
form. Fold ¼ of the egg whites into the chocolate mixture and stir
until well blended. Fold in the remaining egg whites.
Divide the mixture between the soufflé cups, filling just to the rim. Using
a spatula, scrape the edges of the cups clean. (Any chocolate around the rims
of the cups will burn and prevent the soufflés from rising evenly.)
Place the soufflé cups in a deep casserole dish or roasting pan. Space
cups 1" apart on all sides; add water to the depth of ½".
Bake until puffed and set (about 25 minutes).
Combine orange juice, remaining sugar, and white wine in a small saucepan
and cook over medium-high heat until reduced to ½ its original volume.
Dust the soufflés with powdered sugar and serve immediately with the syrup.
