Beat the butter and powdered sugar in the bowl of a stand mixer until creamy.
Beat in the egg yolk and mix until fully combined.
With the mixer on low speed, beat in the salt and flour just until the dough comes together and there is no more visible flour. Careful not to over-mix.
Remove dough from the bowl and press the dough into the tart pan, making sure it is evenly distributed.
Using a fork, prick the bottom of the tart shell to prevent the bottom from puffing up when baking.
Wrap the pan loosely in plastic and chill 30 minutes.
Bake the tart shell at 350F or until the crust is a light golden brown (approximately 13 minutes).
Remove carefully from oven and let rest on a wire rack.
Vanilla Custard
Combine milk and cream in a small saucepan.
Using a sharp knife, split vanilla bean in half lengthways and scrape out seeds. Add bean and seeds to milk mixture.
Place mixture over medium heat. Cook, stirring constantly, for 5 minutes or until hot (do not allow to boil). Remove saucepan from heat. Remove vanilla beans from milk mixture.
In a separate bowl, whisk together egg yolks, cornstarch, and sugar.
Slowly stream the hot milk mixture over egg yolk mixture, whisking constantly.
Return mixture to saucepan over low heat. Cook, stirring constantly, for 10 - 15 minutes or until custard thickens and coats the back of a spoon.
Apple Roses
Over medium heat, combine orange juice, sugar, and butter in a medium-size pot. Remove from heat once mixture boils.
Peel, core, then cut apples in half. Using a very sharp knife or mandolin, slice apples paper thin, roughly 1/8-inch in thickness.
Place the sliced apples in the hot sugar, butter, and orange juice mixture. Leave apples to soak for 10 minutes, or until they are pliable.
Remove the apple slices from the liquid and pat with paper towel if too wet. Lay the apple slices on a plate.
Start with the smaller apple slices first (the centre of rose), roll apple slice so that both ends of the slice overlaps a little. Taking a slightly larger slice, build a second petal on the exterior of the first rolled slice. Continue until you have a fully "bloomed" apple rose.
Arrange apple roses into the custard-filled tart. Serve at room temperature or slightly chilled.