Separate the eggs, setting the egg whites aside. Whisk the yolks in a heatproof bowl.

Place the 200 g sugar and water in a saucepan over medium heat. Stir until the sugar has dissolved, then bring to the boil. Continue cooking until the mixture turns a deep, dark caramel—almost at the “Oops, I’ve burnt it!” stage. Carefully add the cream and vanilla seeds, and continue to boil, stirring until smooth.

Slowly pour the hot caramel over the egg yolks, whisking constantly. Return the mixture to the saucepan and stir over low heat until it thickens slightly and coats the back of a spoon.

Meanwhile, soak the gelatine leaves in a bowl of cold water for 5 minutes, then squeeze out the excess water. (If using powdered gelatine, dissolve it in 30 ml water first.) Add the gelatine to the caramel mixture and stir until completely dissolved. Strain through a fine sieve into a clean bowl and set aside to cool.

Fit the whisk attachment to a stand mixer and whisk the reserved egg whites with the extra 50 g sugar until soft peaks form.

In a separate bowl, whisk the cream to soft peaks, then gently fold it into the egg whites. Carefully fold through the cooled caramel mixture, being careful not to knock out too much air.

note

This rich, silky mousse will keep in the fridge for up to 3 days.