Melt the chocolate and butter together in a double boiler over a low simmer.  Once melted, mix together, then mix in the salt, vanilla extract, and Grand Marnier; set aside to cool a bit.

While that cools, butter and sugar the ramekins.  Once all dishes are done, place ramekins in the fridge so the butter can chill.

Beat egg whites about 30 seconds on medium speed, just until frothy.  Add cream of tartar, then beat until the egg whites have soft peaks.  Add confectioners' sugar, then beat until the egg whites have stiff peaks.

Place egg yolks in a large bowl to beat. Mix sugar and water in a saucepan, then bring to a simmer; simmer until sugar is all dissolved (should only take a couple of minutes).  Beat egg yolks on medium speed, and add syrup (sugar-water mixture) very slowly while beating; beat for about three minutes once done.

Fold egg yolk mixture into chocolate mixture; can use a whisk to make quicker work of this if desired.  Once egg yolk mixture is completely worked into chocolate mixture, fold in 1/4 of egg whites.  When only a few wisps of egg white remain, add remaining egg whites and fold in.

Spoon batter evenly into ramekins, wipe away any mess from the rim, then cover with cling film, then foil.  Place in freezer for up to one month.

When ready to cook, place ramekins straight from freezer (no need to defrost) into preheated 400F/200C oven for 18 minutes.  Serve immediately.