Chocolate Caramel Walnut Tart

Source: Cook Illustrated

Ingredients:

Walnut Crust
1 large egg, separated
1/4 tsp vanilla extract
1/2 c tasted walnuts (2 1/2 oz)
1/2 c (2oz) confectioner's sugar
1/8 tsp salt
5 tbsp cold unsalted butter, cut into 1/2 inch cubes

Caramerl-Walnut Filling and Garnish
1/4 c water
1 c (7 oz) granulated sugar
2/3 c heavy cream
3 tbsp unsalted butter, cut into 3 pieces
1/2 tsp vanilla extract
1/2 tsp juice from 1 lemon
1/8 tsp table salt
16-18 toasted walnut half
1 c (5 oz) tasted walnuts. coarsely chopped

Chocolate Filling
2 large egg yolks
1 tbsp plus 1/2 c heavy cream
1/3 c whole milk
5 oz semisweet chocolate, chopped fine
2 tbsp unsalted butter, cut into 4 pieces

Instructions:

Walnut Crust

1. Beat egg white in bowl with fork until frothy, remove 1 tbsp egg white to second bowl and whisk in yolk and vanilla. Process nuts and suger in food processor until finely ground, 8 to 10 seonds. Add flour and salt and pulse to combine. Scatter butter pieces over flour mixture; pulse to cut butter into flour until mixture resmeble coarse meal, about fifteen 1-second pulses. With machine running, add egg yolk mixture and process until dough forms ball, about 20 seconds. Transfer dough to large sheet plastic wraps and press into 6-inch disk; wrap dough in plastic and refrigate until firm but mallable, about 30 minutes.
2. Roll out dough between 2 large sheets lightly floured plastic wrap to 13-in round, about 1/8-inch thick (if at any point dough becomes too soft abd sticky to work with, slip dough onto baking sheet and freeze or refrigerate until workable). Place dough round on baking sheet and freeze until stiff and cold, about 15 minutes (or refrigerate about 30 minutes). Meanwhile, evenly spray 9 inch tart pan with removable bottom with non-stick cooking spray.
3. Remove dough from freeze; discard top sheet plastic wrap but keep dough on baking sheet. line tart pan with dough. Freeze dough-lined tart pan until firm, about 30 minutes (can be wrapped tightly with plastic wrap and frozen up to 1 month.)
4. Meanwhile, adjust oven rack to middle position; heat oven t0 375 degrees. Set dough-lined tart pan on baking sheet. Spray 12-inch square foil with nonstick cooking spray and press foil inside chilled tart shell; fill with pie weights. Bae until light goilden brown, about 30 minutes, rotating halfway through baking time. Carefully remove foil and weights and continue to bake until golden brown, about 5 minutes longer. Cool on baking sheet on wire rack about 5 mintues, then brush hot crust with served egg white. Reduce oven temperature to 300 degrees.

Caramel-Walnut Filling and Garnish:

1. While crust is cooling, pour water into medium heavy-bottomed saucepan; add sugar to center of the pot to keep granules from adgering to sides of pot. Bring to boil over medium-high heat, covered, swirling pan once or twice to dissolve sugar. Uncover pot and continue to boil, without stirring, until sugar is deep amber, begins to smoke, and registers about 375 degrees on instance read or candy thermometer, 5 to 10 minutes. Remove pan from heat. Carefully add about half of cream, mixture will sputter and steam. Add remaining cream and let bubbling subside. Return pan to low heat and stir with heatprool rubber spatula until caramel is smooth. Add butter and stir until melted. Remove pan from heat; stir in vanilla, lemon juice, and salt.
2. Add walnut halves to caramel and stir to coat; let stand until caramel is slightly thickened, about 8 minutes. Using slotted spoon and allowing excess caramel to drain back into saucepan, transfer walnuts to wire rack set over baking sheet; set aside. Stir chopped walnuts into caramel, then pour mixture evenly into tart shell. Refrigerate, uncovered on baking sheet until caramel is firm and does not slip when pan is tilted, about 20 minutes.

Chocolate Filling:

1. Whisk yolks and 1 tablespoon cream in small bowl. Bring milk and remaining 1/3 cup cream to simmer in small saucepan; off heat, add chocolate and butter, Cover pan and let stand until chocolate is mostly melted, about 2 minutes. Using spatula, stir mixture until smooth; stir in yolk mixture. (Chocolate should be thin and pourable; if too thick to pour evenly, set saucepan over low heat to warm mixture.) Pour filling into caramel-filled tart shell, tilting tart pan as necessary to evenly distribute chocolate to edges of tart. Bake on baking sheet in 300-degree oven until tiny bubbles are visible on surface and chocolate layer is just set (if pan is gently shaken, filling will appear very wobbly because caramel layer is warm), about 25 minutes. Set baking sheet with tart on wire rack; arrange caramel-coated walnut halves on surface of tart, around perimeter. Cool tart until just warm, about 30 minutes, then refrigerate, uncovered, until chocolate is firm, at least 3 hours.