This is so far from being the sort of jelly you'd expect at a children's party as can be imagined! The white currant decoration may be unavailable, but what matters is the drink-made-dessert itself!
If you are unable to find gelatine leaves, you can use powdered gelatine instead. For the UK we recommend 6 teaspoons unflavoured powdered gelatine and for the US 5½ teaspoons unflavored powdered gelatin. At step 2, put 5 tablespoons cold water in a small bowl and sprinkle over the gelatine. Let it stand for 5 minutes to hydrate - it will swell up and become slightly translucent. At step 2, stir the gelatine into the saucepan of warm liquid, until dissolved. Continue as directed.
Recipe posted by Nigella