Yep - equal parts champagne (or whatever sparkling leftover) and sugar, gently heated until the sugar dissolves. It has a delicate champagney flavour. I use it as a simple 1:1 syrup. (I suppose it could also be made in Diffords prefered 2:1 ratio - not sure if the flavour would stand up to that much sugar?)
Had some leftover champagne (weird) and made it into a simple syrup. Used it in the sabot when I didn’t have any sparkling anything. I guess not technically a sabot but DELICIOUS.