Drain lychees into a sieve, collecting the syrup. Cut lychees into quarters. Place one sugar cube each in the hollows of an ice cube tray. Drizzle about 2 drops of angostura on each. Add lychees and frozen raspberries to the sugar cubes in the wells.
Add lychee syrup, possibly topping up with some water. Freeze for at least 4 hours.
To serve, place 2 ice cubes with a shot of brandy in champagne bowls. Fill up with Prosecco.