Put the sugar in a small saucepan and add the 6 tablespoons of water.

Bring to a boil for a few seconds, then set aside.

Whisk the egg yolks in a large heatproof bowl over a pan of simmering water (bain-Marie).

When they are light in color, add the hot sugar syrup and keep whisking until the mixture thickens and forms a ribbon when you pull the whisk up from the yolk mixture.

Remove from the heat and continue to whisk until it’s cool.

Add the liqueur (don’t add more than the 3 tablespoons called for – it’s plenty!) and use a good flexible spatula to fold in the lightly whipped cream.

Freeze for six hours, or overnight.