Your choice of sherry greatly affects the finished cocktail I we ummm'd and ahhhh'd between dry oloroso, palo cortado, and amontillado sherries before...
I tried it with a London Dry, Fino Sherry, Noilly Prat, and a Martini Riserva Speciale Rubino and I must say that this version, although it seems 'simple', evolves quite complex. I accompanied it with an after dinner cheese and what a match !