Ugh ... I find chocolate far too sweet now.
Years ago I was a real addict. I'd regularly eat 4 or 5 bars every day ... I even used to have two bars of chocolate for my breakfast.
Mr M used to ask the local newsagent to buy in a whole box of Creme eggs at a time.

I believe it is what we would call 'Castor Sugar', Summer.

CHOCOLATE MOUSSE #1

6 ounces (170 gram) bitter-sweet chocolate
4 TBLSP unsalted butter. room temp
pinch of salt
1 TBLSP of brandy or light rum or strong coffee or orange flavored liqueur
4 large eggs . separated
2 TBLSP super-fine sugar
1/2 cup heavy whipping cream , plus extra for garnish if desired

1.) using a glass dish, melt chocolate in microwave for 2 minute on low temp

2.) Wisk butter into choc, 1 tblsp at a time, repeat until butter is used up.

3.) Add flavor of your choice: brandy, coffee etc

4.) add salt and stir until very well incorporated.

5.) Wisk in egg yolks one at a time, being sure to fully incorporate each time.

6.)Place a metal bowl over slightly simmering water and stir egg whites until warm (about 2 minutes)

7.) Remove pan from water and beat until soft peaks form. Raise mixer speed to high and slowly add sugar. Beat to stiff peaks.

8.) Lightly FOLD beaten egg whites into the chocolate. Gently FOLD remaining egg whites into the chocolate until fully incorporated.
Set aside.

9.) Whip heavy cream to soft peaks; gently FOLD whipped cream into the choc/egg white mixture.

10.) Spoon into tulip glasses.

11.) cover and chill at least 2 hours

12.) top with additional whipped cream if desired.

13.) serve cold

I believe it is what we would call 'Castor Sugar', Summer.

Ms d00d likes the dark bitter stuff. Those creme eggs are at the yukky end of the scale.

And This:

https://www.choccywoccydoodah.com/cakes.html

No. Super-fine sugar is regular sugar but finely ground.

I believe it is what we would call 'Castor Sugar', Summer.

Is superfine sugar what we would call icing sugar ? A soft white powder with no granules?..I suspect it is.

Your recipe sounds lovely might be nice with a small side order of sweet black cherries.

Thanks for the recipe and info. I did not realize this and I’ve never in my life made chocolate mouse but I’ve always wanted to