Soften the gelatin in cold water.
Scrape the seeds from the vanilla pod and mix with a little powdered sugar.
Whisk the cream cheese with crème fraîche, powdered sugar, and vanilla.
Add grated lemon zest.
Whisk the cream until lightly stiff.
Heat the lemon juice in a pot, squeeze out the gelatin, and melt it in the lemon juice.
Add 1 large tablespoon of cheese mixture to the warm lemon juice.
Stir well.
Add another large tablespoon of cheese mixture.
Stir.
Pour the now tempered lemon mixture into the remaining cheese mixture and whisk quickly together.
Fold the lightly whipped cream into the cheese mixture and pour it over the biscuit base.
Let it set for at least 3 hours in the fridge.