Calvados is underused but with some reason. It can be a little harsh. The best drink I have had made with it was a Calvados Old Fashioned which tamed the rougher side of the spirit.
Here I have also tried to soften the flavours but wanted Calvados to still be the prominent component and flavour. To my taste I think this works really well.
The cherry notes of the Byrrh, the clove of the Falernum and the chocolate notes of the bitters are all flavours that classically work well with apple.
The name? Ash Sayeffe is phonetically how you say the letters HCF in French. HCF stands for Homme, Chapeau, Fauve. Which in English means Man, Hat, Tan. And this is sort of a Manhattan with French ingredients. And Scottish. And Barbadian. Get it? Blimey. You know you've lost your way when naming a drink if you spend longer explaining that than the drink itself...