Place milk in a heavy-based saucepan with the vanilla bean. Bring to the boil. While this is coming to the boil, combine the caster sugar and corn our in a bowl, whisking to blend the dry ingredients together. Add whole eggs and egg yolks.
When the milk has started to lift, remove the vanilla bean, scrape it against the side of the pan and stir in the remaining seeds. Slowly add approximately a quarter of your hot milk to your sugar and egg mixture, constantly whisking.
Add your sugar mixture back to the milk on the stove and cook until silky smooth and thickened. Remove the crème patissier from the pan and place in a bowl. Cover firmly with cling lm and place into the fridge to chill.
Ensure butter puff pastry is flattened out to a 35cm square. Using a fork, prick tiny holes all over the pastry to avoid excess shrinkage and rise from the butter pastry. Place on a tray and bake at 200°C for 20 minutes. Flip over, then bake for a further 5 minutes. Once cooked, remove from oven and leave to cool.
Once the pastry has cooled, cut into three equal strips. Pipe crème patissier in between the pastry, inverting the top layer so you have a smooth surface to decorate.
Warm your white fondant to 37°C and spread over the top, feathering with warm chocolate to decorate.
Once the fondant is set, you can cut your mille feuille into six equal portions using a serrated bread knife.
Chef’s Tip: At The Gumnut Patisserie we produce our butter puff pastry in a classical way over many days. This isn’t practical in a home kitchen so you can source a high quality pre-rolled butter puff pastry from your providore.