How to Make It
Preheat the oven to 325°. Butter eight 1/2-cup ramekins and set them in a large roasting pan. In a small saucepan, heat the milk until bubbles appear around the edge, then pour it into a glass measuring cup. Wipe out the pan and add the chopped chocolate and the butter. Cook over low heat until the chocolate is barely melted, about 2 minutes. Whisk in the hot milk and remove the pan from the heat.
In a large bowl, beat the egg whites to firm peaks. Add 2 tablespoons of the sugar and continue beating until glossy.
In a large mixing bowl, using a handheld mixer, beat the egg yolks with 1/2 cup of the sugar and the salt at high speed until pale, about 4 minutes. Add the flour and vanilla and beat until smooth. Beat in the chocolate mixture, then fold in the beaten egg whites. Pour the batter into the prepared ramekins.
Pour enough hot water into the roasting pan to reach halfway up the side of the ramekins. Bake the puddings for about 35 minutes, or until puffed and set. Transfer the ramekins to plates and let cool to warm.
In a mixing bowl, whip the heavy cream to soft peaks. Add the remaining 1 tablespoon of sugar and the liqueur and whip until firm. Spoon a dollop of whipped cream on each pudding, sprinkle with the grated chocolate and serve.
Two excellent and widely available brands of bittersweet chocolate are Lindt and Valrhona.