1. Soak the gelatin leaves in a bowl of cold water. Line a 1-liter charlotte mold with plastic wrap, allowing the edges to hang over.
2. Drain the pears in a colander, slice them into thin slices. Collect the juice and pour it into a shallow plate. Cut the ladyfinger biscuits to a height of 7 cm, quickly dip them in the syrup, and press them against the inner wall of the mold, with the rounded side facing outwards. Place the leftover pieces in the syrup. Arrange 5 biscuits at the bottom of the mold.
3. Heat the milk in a saucepan with the split and scraped vanilla bean. In a large bowl, whisk the eggs with the cornstarch and sugar, add a little hot milk and beat with a fork. Pour the mixture back into the saucepan after removing the vanilla bean. Cook over low heat, stirring, for 3 to 4 minutes until the custard thickens. Remove from heat, add the squeezed gelatin leaves and mix. Let it cool slightly.
4. Arrange a layer of pears at the bottom of the mold, add some pieces of biscuits, pour a little custard over it, then add the remaining ingredients, alternating them. Arrange the remaining pears on top in a decorative manner. Chill for at least 6 hours. When ready to serve, unmold the charlotte by lifting it and place it on a serving dish.