1. Preheat oven to 350°F(175°C). Lightly grease 4-ounce souffle cups as needed. Sprinkle a small amount of sugar in each souffle cup. Rotate the cups to evenly coat the insides with the sugar. Discard any excess sugar.
2. Combine 3/4 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, about 10 minutes. Remove mixture from heat. Seperately whisk together egg yolks, vanilla, and orange liqueur; blend mixture into chocolate.
3. Combine the egg whites and 1/4 cup** of sugar; beat until soft peaks form. Fold 1/4 of the egg whites into the chocolate mixture and stir until well blended. Fold in the remaining egg whites.
4. Divide the mixture between the souffle 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 souffles from rising evenly.)
5. Place the souffle cups in a deep casserole dish or roasting pan. Space cups 1-inch apart on all sides; add water to the depth of 1/2-inch. Bake until puffed and set, about 25 minutes.
6. Combine orange juice, remaining sugar, and white wine in a small saucepan and cook over medium-high heat until reduced to 1/2 its original volume. Dust the souffles with powdered sugar and serve immediately with the syrup.