# What You'll Need:
→ Tart Crust
01 - 7 ounces all-purpose flour
02 - 3.5 ounces cold unsalted butter, cubed
03 - 1.75 ounces powdered sugar
04 - 1 large egg yolk
05 - 1-2 tablespoons cold water
06 - Pinch of salt
→ Custard Filling
07 - 5.25 ounces white chocolate, finely chopped
08 - 1 cup plus 1 tablespoon heavy cream
09 - 3 tablespoons whole milk
10 - 4 tablespoons elderflower cordial
11 - 3 large egg yolks
12 - 2 tablespoons granulated sugar
13 - 1 teaspoon vanilla extract
→ Rhubarb Topping
14 - 10.5 ounces rhubarb, trimmed and cut into 2-inch batons
15 - 2 tablespoons granulated sugar
16 - Zest of 1 lemon
17 - 2 tablespoons elderflower cordial
# How to Make It:
01 - Pulse flour, butter, powdered sugar, and salt in a food processor until mixture resembles breadcrumbs. Add egg yolk and 1 tablespoon cold water; pulse until dough begins to come together, adding more water if needed. Shape into a disk, wrap in plastic, and refrigerate for 30 minutes.
02 - Roll out dough on a floured surface to fit a 9-inch tart tin. Press into tin, trim edges, and refrigerate for 15 minutes.
03 - Preheat oven to 350°F. Line crust with parchment and baking beans; blind bake for 15 minutes. Remove beans and parchment, bake 5-7 minutes more until golden. Allow to cool completely.
04 - Heat cream and milk in a saucepan until steaming but not boiling. Whisk egg yolks, sugar, and vanilla in a bowl until pale. Slowly pour hot cream mixture into yolks, whisking constantly.
05 - Return mixture to saucepan over low heat, stirring until slightly thickened and coating the back of a spoon. Remove from heat.
06 - Add white chocolate and elderflower cordial; stir until smooth. Pour custard into cooled tart shell. Refrigerate for at least 1 hour until set.
07 - Preheat oven to 375°F. Arrange rhubarb batons in a single layer in a baking dish. Sprinkle with sugar, lemon zest, and drizzle with elderflower cordial. Cover with foil and roast for 15 minutes. Remove foil, roast 5-8 minutes more until tender but not falling apart. Cool completely.
08 - Arrange cooled rhubarb over set custard. Optionally brush with extra elderflower cordial for shine. Refrigerate until ready to serve.
