- 1/2 vanilla bean, split lengthwise
- 1 1/4 cups whole milk
- 1/3 cup sugar, divided
- 1 1/2 tablespoons all-purpose flour
- 1 tablespoon cornstarch
- 1 whole large egg
- 1 large egg yolk
- 1 1/2 tablespoon unsalted butter, cut into bits
- 2 pounds Golden Delicious apples (about 4)
- 1 pound frozen all-butter puff pastry, thawed
- 3 tablespoons unsalted butter, melted
- 3 tablespoons light corn syrup
- 2 teaspoons water
- Equipment: a 6-inch-diameter bowl or plate; a 1 1/2-inch round cookie cutter; a 10-inch disposable pastry bag or sealable plastic bag
- Accompaniment: vanilla ice cream
- Scrape seeds from vanilla bean with tip of a paring knife into a small heavy saucepan. Add pod, milk, and 3 Tbsp sugar and bring just to a boil, whisking to dissolve sugar.
- Meanwhile, whisk together flour, cornstarch, remaining sugar, and a pinch of salt in a bowl. Whisk together whole egg and yolk in another bowl, then whisk in flour mixture until smooth.
- Add one third of hot milk mixture to yolk mixture (to temper) in a slow stream, whisking, then add to milk mixture remaining in saucepan, whisking. Bring custard to a boil over medium heat, whisking, then boil, whisking, 2 minutes. Remove from heat and stir in butter until melted.
- Transfer pastry cream to a bowl and chill, its surface covered with wax paper, until no longer hot, at least 30 minutes.
- Preheat oven to 400°F with racks in upper and lower thirds. Line 2 large baking sheets with parchment paper.
- Peel and core apples, then cut into 1/8-inch-thick wedges.
- Roll out pastry on a lightly floured surface with a lightly floured rolling pin 1/8 inch thick and cut out 8 (6-inch) rounds using inverted bowl or plate as a guide. Punch out center of each round with cookie cutter and transfer to baking sheets.
- Discard vanilla pod and transfer pastry cream to pastry bag. Snip a 1/3-inch opening and pipe pastry cream onto pastry in a ring around center (there will be some cream left over). Arrange overlapping apple slices on pastry, covering the cream, then brush with melted butter.
- Bake tarts, switching position of sheets halfway through, until edges of apples are pale golden, about 15 minutes.
- Meanwhile, stir together corn syrup and water until smooth.
- Remove baking sheets from oven and flip each tart over with a large spatula. Generously brush pastry with some of corn syrup mixture.
- Continue to bake, switching position of sheets halfway through, until pastry is shiny and golden, about 15 minutes more. Cool 10 minutes.
- Serve tarts, pastry side up, warm or at room temperature.