1. In a saucepan, pour in the water and add the grapes. Bring to a quick boil and remove from heat, then add the rum, cover and let it steep while you prepare the pastry cream.

2. In a bowl, mix together the sugar, egg yolks, and whole eggs. Whisk the mixture and gradually incorporate the flour. Set aside.

3. Submerge the vanilla bean in the milk and bring to a boil.

4. Pour the milk mixture over the egg mixture, whisking constantly, and transfer the mixture to a clean saucepan.

5. Bring to a boil again, whisking constantly and making sure not to let the cream stick to the bottom. Let cool, covering with plastic wrap directly on the surface of the cream to prevent a crust from forming.

6. Meanwhile, in a saucepan of boiling water, submerge the whole plantain bananas, pierced to prevent them from bursting. After no more than 5 minutes of cooking, drain the plantains and let them cool to handle without burning yourself.

7. Peel the banana gently without breaking it and flatten it slightly.

8. Spread the pastry cream over the surface and top with rum-soaked grapes, then sprinkle with cinnamon.