Let the chocolate melt together with the butter. (This works best in the microwave!).
Separate the eggs. Beat the yolks with 2 tbsp. sugar until very creamy. Whip the egg whites with the remaining sugar until stiff peaks form.
Fold the slightly cooled but still liquid chocolate-butter mixture into the egg yolk foam and fold in the snow.
Pour into a suitable bowl and set in the refrigerator for at least 60 minutes.
The chocolate mousse will keep in the refrigerator for at least 24 hours.
Preparation Tip:
Feel free to use better chocolate - the more delicious the result will taste!