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 overmix. Remove dough from the bowl and press the dough into the tart pan, making sure it is evenly distributed (watch out for the edges of the tart pan!). 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 410F or until the crust is golden brown (approximately 15 minutes). Remove carefully from oven and let rest on a wire rack. Let cool completely before filling with 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 over medium heat. Cook, stirring constantly, for 5 minutes or until hot (do not allow to boil). Remove saucepan from heat.
Whisk egg yolks, cornflour, and sugar in a heatproof bowl until well combined. Remove vanilla beans from milk mixture. Pour 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 metal spoon.
Over low heat, combine orange juice, sugar, and butter in a medium-size pot.
Slice apples with mandolin.
Place the slices apples in the sugar, butter, and orange juice mixture. Leave apples to soak for 10 minutes until they are pliable.
Start with the smaller apple slices first, 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.
Apple Rose Vanilla Custard Tart by Amy of Constellation Inspiration