In a large bowl, combine the cornflakes, granulated sugar, and melted butter until everything is thoroughly coated.

Firmly press the cornflake mixture into a lined baking dish, creating an even layer and chill in the refrigerator for about 30 minutes.

In a saucepan over medium heat, warm the whole milk with the split vanilla bean and scraped seeds until it’s steaming but not boiling.

In another bowl, whisk together the egg yolks and granulated sugar until the mixture is smooth.

Gradually add the warm milk to the egg mixture, whisking constantly to avoid cooking the yolks.

Return the mixture to the saucepan and cook gently, stirring frequently, until it thickens slightly for about 5-7 minutes.

In a small bowl, sprinkle the powdered gelatin over one tablespoon of water. Let it sit for a minute, then stir it into the warm custard until completely dissolved.

In a chilled mixing bowl, whip the heavy cream with the powdered sugar until soft peaks form.

Gently fold the whipped cream into the cooled custard mixture.

Spread the filling evenly over the chilled cereal crust. Cover and refrigerate for at least 2 hours or until fully set.