I think this is the best use of vermouth I've ever tasted. Blew me away.

1. This recipe is too watery. WAY too watery; if you want a lighter (or budget) version, sure, but I suggest 2oz *heavy* cream. Reserving some of the fizz means you'll have to pour it over the head, which will break up the head. Instead, empty the shaker thru a strainer, add a splash of soda, then get the rest of the hard foam out. Wait a minute, then run more soda down the edge of the glass to lift the head above the rim. This is the classic New Orleans technique.

This comment is correct. Heavy cream (although I only used the amount from this spec) and pouring the soda after allowing the foam the set are both necessities.