- 3/4 cup unbleached all purpose flour
- 3/4 cup assorted nuts (such as walnuts, almonds, and hazelnuts), toasted, cooled
- 1/4 cup sugar
- 3/4 teaspoon salt
- 6 tablespoons (3/4 stick) chilled unsalted butter, diced
- 1 large egg yolk
- 2 teaspoons water
- 1/4 teaspoon unflavored gelatin
- 3 large egg yolks
- 1/4 cup sugar
- 1 1/2 tablespoons cornstarch
- 1 cup whole milk
- 1/2 vanilla bean, split lengthwise
- 1/2 cup sour cream
- Santa Rosa Plum Compote
- Butter bottom of 9-inch tart pan with removable bottom. Finely grind flour, nuts, sugar, and salt in processor. Add 6 tablespoons butter. Using on/off turns, blend until coarse meal forms. Add egg yolk; blend until moist clumps form. Press dough over bottom and up sides of pan. Pierce crust with fork. Freeze until firm, about 30 minutes.
- Preheat oven to 400°F. Bake crust until golden, 13 to 14 minutes. Cool completely.
- Place water in very small cup. Sprinkle gelatin over. Let stand until gelatin softens, about 10 minutes.
- Whisk egg yolks, sugar, and cornstarch in medium bowl to blend. Place milk in medium saucepan. Scrape in seeds from vanilla bean; add bean. Bring milk to simmer. Gradually whisk hot milk mixture into yolk mixture. Return to same saucepan. Stir over medium-high heat until custard thickens and boils, about 2 minutes. Remove from heat. Scrape in gelatin mixture and stir to dissolve. Let stand 5 minutes.
- Transfer custard to metal bowl. Discard vanilla bean. Set bowl over another bowl filled with ice and water; stir until cool but not set, about 15 minutes. Fold in sour cream. Spread filling evenly in crust. Chill tart until filling sets, at least 2 hours and up to 6 hours.
- Cut tart into wedges. Spoon plum compote over and serve.