Mix flour and salt in a large bowl. Cut in cold butter with a pastry cutter or your fingers until crumbly.
Add ice water, 1 tablespoon at a time, until the dough forms. Shape into a disk, wrap, and chill for 30 minutes.
Roll dough into a 12-inch circle. Press into a 9-inch pie dish and trim the edges.
Line with parchment, fill with pie weights, and bake at 375°F (190°C) for 15 minutes. Remove weights and bake 5 more minutes until lightly golden. Let cool completely.
Whisk egg yolks in a bowl. In a saucepan, combine sugar and cornstarch. Whisk in milk until smooth. Cook over medium heat, stirring constantly, until thick—about 8 minutes.
Slowly whisk 1 cup of the hot mixture into the yolks, then return everything to the pan. Cook 2 more minutes while whisking. Remove from heat and stir in butter, vanilla, and bourbon.
Pour the warm filling into the cooled crust. Smooth the top. Press plastic wrap onto the surface. Chill at least 4 hours, or overnight for best texture.
Before serving, warm caramel sauce until pourable. Drizzle over the pie. Top with toasted pecans and sprinkle with flaky sea salt, if desired.