Split and scrape the seeds from the vanilla bean. Heat the milk, sugar, and vanilla seeds in a medium pot and bring to a boil.

Whisk the egg yolk and half egg with the cornstarch in a bowl. Temper the hot milk into the egg mixture by adding it slowly while whisking constantly, then return the mixture to the pot over medium heat and whisk until it thickens. Boil for a full minute while whisking, then pour onto a plastic-wrap-lined pan, cover with another sheet of plastic wrap, poke holes in the top, and cool completely.

If the puff pastry is frozen, let it rest on the counter just until pliable but still cold. Cut a rectangular base in your desired size, then cut four strips approximately 2cm wide to form the border walls.

Brush the top of the base with egg wash and press the strips along each edge to create a raised border. Dock the base with a fork to give steam controlled exit points, then chill the assembled tart for at least 45 minutes.

Brush only the top surface of the border with egg wash, taking care not to let it drip down the cut sides. Sprinkle with raw sugar and return to the refrigerator if the pastry has softened.

Bake at 375°F convection or 400°F conventional on a parchment-lined baking sheet for 12 to 20 minutes, until the border is deep golden brown and the layers are visible on the sides. Cool completely before filling.

Beat the chilled pastry cream in a stand mixer with the paddle attachment or by hand until smooth and spreadable. Mix in Bourbon to taste if using. Spread the cream into the cooled tart shell, filling just below the top of the border.

Arrange the fruit over the cream, refrigerate briefly before serving, and serve the day it is assembled.