For the meringue with chocolate sauce, first beat the egg whites with a little sugar until stiff. Add the remaining sugar and continue beating.
For the chocolate sauce, bring all ingredients except the chocolate to a boil. Add the chocolate and stir until it is completely dissolved.
Grease a bowl with the butter. Sprinkle a little fine crystal sugar on top. Pipe in a quarter of the snow using a piping bag. Microwave on the highest setting for about 15 seconds. Turn out onto baking paper. Repeat with remaining beaten egg whites three more times, making 4 servings total. Work quickly.
Arrange meringue with chocolate sauce and serve immediately.