01 - Pulse flour, powdered sugar, and salt in a food processor. Add cold butter and pulse until mixture resembles coarse crumbs. Add egg yolk and pulse. Drizzle in cold water, 1 tablespoon at a time, until dough just comes together.
02 - Turn dough onto a floured surface, shape into a disk, wrap in plastic, and refrigerate for at least 1 hour.
03 - Preheat oven to 350°F. Roll dough to fit a 9-inch tart pan. Press into pan and trim excess. Prick base with a fork. Line with parchment and fill with pie weights or dried beans. Bake for 15 minutes. Remove weights and parchment; bake 10 more minutes until golden. Cool completely.
04 - Heat milk and vanilla bean (or extract) in a saucepan until just simmering. Remove from heat. Meanwhile, whisk egg yolks, sugar, and cornstarch until smooth.
05 - Gradually whisk hot milk into egg mixture. Return to saucepan and cook over medium heat, whisking constantly, until thickened and bubbling for 2–3 minutes. Remove from heat and stir in butter until smooth.
06 - Transfer custard to a bowl, cover with plastic wrap touching the surface, and refrigerate until cool, at least 1 hour.
07 - Spread cooled custard evenly in tart shell. Arrange fresh fruit decoratively over custard.
08 - Warm apricot jam and water in a small saucepan until melted. Strain if needed. Brush glaze gently over fruit for shine. Refrigerate assembled tart for 1 hour before serving.