Cut vanilla bean in half, scrape out seeds, and combine with sugar, cornstarch, salt, egg, egg yolks, and milk in a saucepan; whisk until combined.

Cook over medium heat, stirring constantly, until thick, about 10 minutes.

Remove from heat, whisk to release steam, add butter, and stir until melted.

Strain through a fine sieve and cover with plastic wrap directly on the surface. Refrigerate until chilled, at least 2 to 3 hours.

Preheat oven to 425?F (220?C) and line a baking sheet with a silicone liner.

Combine butter, water, and salt in a saucepan over medium-high heat; bring to a simmer.

Add flour and stir until a dough forms, continuing to cook until a starchy film forms in the pan, about 1 minute.

Transfer to a bowl, add one egg, and mix in until combined. Repeat with the second egg until a sticky dough forms.

Transfer dough to a pastry bag and pipe two 6-inch heart shapes on the prepared baking sheet.

Bake in preheated oven until browned, about 30 minutes. Turn off heat, leave pastries in oven with the door ajar for 1 hour.

Slice hearts in half horizontally.

Pipe chilled pastry cream into the bottom halves of each heart and then place the top halves on the cream.

Heat cream until simmering.

Pour hot cream over chocolate chips in a bowl; let sit for 2 to 3 minutes, then whisk until thick and shiny.

Spoon ganache on top of each heart and refrigerate until firm, about 15 minutes.

Fill the center of each heart with raspberries and sift cocoa powder and powdered sugar over top before serving.