1 Preheat the oven to 350°F. Grease and flour a 9×13-inch baking pan.

2 In a medium bowl, whisk together flour, baking powder, and salt. In a large bowl, cream together the butter and sugar until light and fluffy. Beat in the eggs one at a time, then add the vanilla. Alternate adding the dry ingredients and milk, beginning and ending with the flour mixture. Mix just until combined.

3 Pour the batter into the prepared pan and bake for 25 to 30 minutes, or until a toothpick inserted in the center comes out clean. Let the cake cool for 10 minutes, then use the handle of a wooden spoon to poke holes evenly across the surface.

4 While the cake bakes, make the pastry cream. In a medium saucepan, heat the milk over medium heat until just steaming. In a separate bowl, whisk together the sugar, egg yolks, and cornstarch until smooth and pale.

5 Slowly pour half the hot milk into the egg mixture while whisking to temper the eggs. Return the mixture to the saucepan and cook over medium heat, whisking constantly, until thickened and bubbling. Remove from heat and stir in the butter and vanilla. Let it cool slightly, then pour over the cake, spreading to fill the holes and cover the surface. Chill the cake for at least 1 hour.

6 To make the ganache, heat the heavy cream in a small saucepan until steaming but not boiling. Pour over the chopped chocolate in a heatproof bowl. Let sit for 2 minutes, then stir until smooth and glossy.

7 Pour the ganache over the chilled cake and spread evenly. Refrigerate the cake for another hour or until fully set before serving.