This recipe does contain raw eggs, which is a no-no for some including those who are pregnant, have compromised immune systems, or are under three years old. I’ve included a version that uses cooked eggs in this in-depth post on making Matcha Mousse just in case.
It is important for the mixer and bowl to be clean between making the meringue and whipped cream portions of the mousse or the cream will not whip properly.   If you’d like to temper the chocolate so it is shiny, you will need an instant-read thermometer. Melt about 3/4 of the chocolate in the bain-marie until it reaches 122 to 131 degrees Fahrenheit. Remove it from the bain-marie, add the rest of the chocolate, and stir until it cools to 82 to 84 degrees Fahrenheit. You can do this over a bowl of cold water. Finally, heat it over the bain-marie again until it reaches 88 to 90 degrees Fahrenheit.   The disc mold I use is no longer being made, but here is the closest thing I could find that would work well. The one I have is 1/12 inch deep, and the circles are 1.25 inch in diameter. Don’t let equipment stop you, you can make the gelt in the muffin tins with muffin liners!   Muffin tin instructions: spray your muffin tin with coconut (or a flavorless) oil spray. If using a large muffin tin, add two teaspoons of the chocolate to each well. If using a mini muffin tin, add one teaspoon of chocolate to each well. Refrigerate for minimum 20 minutes.