Choca Mocha Mousse

Another dessert recipe this week, from the same magazine as the last one (OK, it's the Weight Watchers magazine). Yes, I made a few changes to it - artificial sweeteners are one of the things I absolutely will not use, and this recipe called for them. So of course I replaced that ingredient with good old sugar.
One of the other things used in this recipe is something I've never used before, so I was a little worried about it - gelatine. For some reason, I have the idea that it's a tricky thing to work with, and if you don't get it exactly right things are going to turn out inedible. Well, I followed the instructions and things worked out just fine. In fact, it looked just like the picture. This was reassuring - when I was pouring the mousse into the glasses, it was quite worrying to see that some of it was nicely foamy, but that there was a good quantity of liquid too. Pouring the liquid in, it settled to the bottom, with the 'foam' sitting on top. I really didn't think it was going to set, but it did, in two distinct and complementary layers - a denser mousse on the bottom, with a lighter one on the top. Very nice, and one to make again. I'm tempted to try variations, but there's that fear of it all going so wrong...

Recipe:
3 grams leaf gelatin (2 sheets)
40 grams dark chocolate (I use Green & Black's)
75 millilitres strong black coffee
25 millilitres skim milk
2 egg whites
2 teaspoons caster sugar

Cut the gelatine into strips and soak in cold water for 10 minutes to soften.
Melt the chocolate in a heatproof bowl.
In a small pan, heat together the coffee and milk. Do not allow to boil.
Squeeze the excess water from the gelatine. Add to the hot coffee and stir to dissolve.
Whisk the egg whites until soft peaks form. Add the sugar and whisk to combine.
Gently fold the egg whites into the chocolate.
Drizzle the coffee into the mixture, and fold in gently, keeping as much volume as possible.
Divide between two 150ml glasses or ramekins.
Cover and chill for about 2 hours until set.