1. Prepare the Crust:

1. In a food processor, combine flour, butter, and sugar until crumbly. Add egg yolk and ice water; pulse until dough forms. Wrap in plastic and chill for 30 minutes.
2. Preheat oven to 375°F (190°C). Roll dough into a circle, fit into a 9-inch tart pan, and prick with a fork. Line with parchment and pie weights; bake for 15 minutes. Remove weights and bake 5 more minutes until golden. Cool.
3. In a saucepan, heat milk and vanilla bean seeds over medium until steaming. In a bowl, whisk egg yolks, sugar, cornstarch, and salt until smooth. Gradually whisk in hot milk, then return to saucepan. Cook, stirring constantly, until thick. Strain into crust.
4. Chill tart for at least 4 hours until set. Serve at room temperature or chilled.