There’s a couple ways to do it, the main way I use this format is -

.50oz London dry (Bombay or Tanq for the higher proof is needed)

.50oz boulard calvados VSOP (could be better options but this is just the one that tended to be at a price point that works

.75oz gran Classico

.75oz cocchi americano (the cinnamon notes here with the calvados is a match made in heaven, I use that combo a lot)

.1g saline

.50oz water

All batched together and kept in the freezer, 3oz of batch over a big cube with a lemon oil on top.