The easiest and delicious Chocolate mousse with only 2 ingredients

We are a chocolate lovers family trying always to find healthy options and easy recipes in order to indulge our cravings, so when I found out this recipe I decided to try it. I found out this two ingredients chocolate mousse recipe in the blog eat, live, run , and it was a double bonus when I saw it was from never than less famous 3 Michelin stars chef Heston Blumenthal. So prepare yourselves here comes the recipe (for 4 people): 9.35 ounces (or 265 g) bittersweet chocolate (at least 70% cocoa), coarsely chopped 1 cup of water 4 tbsp sugar (optional - if you don't add the sugar you will have a really intense chocolate flavour, so if you prefer a sweeter and milder chocolate flavour, by all means, add the sugar) Place a bowl on top of another slightly larger bowl - filled with ice and cold water. The bottom of the top bowl should touch the ice. Set aside. Put the chocolate and the water (and sugar if you are...