How to Make It
Preheat the oven to 350°. Spray six 6-ounce ramekins with vegetable oil–flour baking spray; line the bottoms with parchment or wax paper and spray the paper.
In a small bowl, whisk the egg yolks with 2 tablespoons of the milk and the vanilla. In a medium bowl, beat the butter with the flour, sugar, baking powder and salt at low speed until smooth. Beat in the remaining 1/4 cup of milk and the heavy cream, then beat at medium speed until fluffy, about 2 minutes. Slowly beat in the egg yolk mixture. Scrape the batter into the ramekins and bake for 25 minutes, or until the cakes are puffy and golden. Let cool for 15 minutes, then invert the cakes onto a rack to cool completely. Discard the paper.
In a saucepan, heat the milk with the vanilla bean and seeds. In a small bowl, whisk the egg, sugar, flour, cornstarch and salt. Whisk in half of the hot milk, then scrape the mixture into the saucepan and whisk over moderate heat, until thick, about 3 minutes. Off the heat, whisk in the butter and vanilla. Strain the pastry cream into a bowl; discard the vanilla bean. Press plastic wrap onto the surface of the pastry cream and refrigerate for 1 hour.
In a small saucepan, heat the heavy cream and corn syrup. Off the heat, whisk in the chocolate, vanilla and salt until smooth. Transfer to a bowl and let cool slightly.
Split each cake horizontally. Spoon the pastry cream between the layers. Spoon the glaze on top of the cakes, letting it drip down the sides. Transfer the cakes to plates and serve.