Crush the cookies, add the melted butter, and mix to form a dough. Press firmly into the bottom of an 18 cm (7-inch) cake ring. Chill in the refrigerator.

Soak the gelatin sheets in cold water for 15–20 minutes. Meanwhile, make a custard: Split the vanilla bean and scrape the seeds onto the egg yolks. Whisk the yolks with the vanilla seeds and sugar until slightly pale. Mix in the milk. Pour everything into a saucepan and cook over low heat, stirring constantly. Remove from heat just before boiling, when the custard thickens and coats the spatula.

Off the heat, add the drained gelatin. Let cool, stirring occasionally. Whip the cream until it forms soft peaks. Gently fold the whipped cream into the cooled custard using a spatula.

Make a dry caramel with the sugar. Bring the cream to a boil and add it to the caramel. Mix well. Return to low heat and cook until thickened: when you lift the spoon, it should coat the back. Let cool slightly. Add the butter and mix well into the caramel. Finally, melt the gelatin into the caramel. Press and smooth the cookie base again and chill for 30 minutes.

Pour the vanilla Bavarian cream into the cake ring, cover, and refrigerate immediately. After 1 hour, pour the caramel sauce on top.