Fill a 60 to 90 ml ceramic espresso cup with hot water and let it sit for 1 minute while you grind. Pour it out and dry the cup, because a cold cup cools the espresso before the grappa goes in.
Grind 8 g of coffee fine, dose it into the portafilter basket, and tamp it level with firm, even pressure.
Pull the shot with 93 C / 200 F water at 9 bar for 25 to 30 seconds, until you have 30 ml of espresso with a thick, reddish-brown crema. Stir in the sugar now if you're using it.
Measure 10 ml of grappa and pour it straight into the hot espresso. Give the cup one slow stir, then serve on a saucer with a teaspoon and drink within 3 minutes.