Divide the grappa between two long, preferably transparent, glasses. Add the sugar to the espresso and stir well (sugar must dissolve completely). Then pour about two thirds of the sugar espresso into the glasses with the grappa. Add the rest of the sugar espresso to 125 ml milk and mix. Now carefully pour the mixture into the glasses with the grappa espresso. There is a separation of layers (similar to latte macchiato). Froth the rest of the milk into milk foam, e.g. with a milk frother. Then distribute the milk foam between the two glasses and you`re done.
Of course, you can also put patterns on the milk foam with cocoa powder.