For the top of the Champagne Macarons, I simply mixed a tiny bit of champagne with some rose dust luster, and brushed on top of the shells.
First, make sure you reduce the champagne. This will make sure you have a concentrated champagne taste, and it will help evaporate the alcohol of the champagne also.
Then, pour the hot champagne over chopped white chocolate. Make sure to use high quality white chocolate. Don’t use chocolate chips, they won’t work well.