Once cool, start whipping the mixture at high speed. You can use a whisk attachment, I suggest not trying to do this by hand unless you have strong arms. It can take up to 15-20 minutes to get it to firm peaks.
Once you reach that stage, mix ¼ tsp cream of tartar with 2 cups of icing sugar and gradually add that in, whipping it- whip it good…
Continued with next photo…