Working over a large bowl, sift 1/2 cup of sugar with the cocoa, cornstarch and
salt. Whisk in 1/2 cup of milk to make a smooth paste. Scrape the bottom of the
bowl with a rubber spatula to be sure everything is well mixed.
Melt the finely chopped semisweet chocolate in a double boiler.
In a nonstick medium saucepan combine the heavy cream with the remaining 1 1/2
cups of milk and 1/2 cup of sugar and simmer over a moderately high heat stirring
nonstop for 30 seconds.
Reduce the heat to moderately low and stir in the cocoa
paste and the melted chocolate from the double boiler, whisking constantly. Simmer
for 3 minutes.
Add the vanilla extract and stir in the gelatine with 1/3 cup of
water. Blend well. Sprinkle 1/4 cup of Grand Marnier over, and stir with spatula
until the pudding is smooth.