- 1 1/2 cups all purpose flour
- 1/2 cup (1 stick) chilled unsalted butter, cut into 1/2-inch cubes
- 4 tablespoons (or more) ice water
- 1 cup sugar (preferably baker's sugar or other superfine sugar)
- 1 cup heavy whipping cream
- 1/4 cup (1/2 stick) unsalted butter, room temperature
- 2 teaspoons vanilla extract
- 2 ounces bittersweet (not unsweetened) or semisweet chocolate, chopped
- 2 ounces semisweet chocolate, chopped
- 2 1/2 cups (about 9 ounces) walnuts, toasted, cut into 1/2-inch pieces
Blend flour and salt in processor 5 seconds. Add butter to processor. Using on/off turns, blend until coarse meal forms. Add 4 tablespoons ice water. Blend until dough just begins to come together, adding more ice water by teaspoonfuls if dry. Gather dough; flatten into disk. Wrap; chill at least 1 hour.
Roll out dough on lightly floured surface to 14-inch round. Transfer dough to 11-inch-diameter tart pan with removable bottom. Cut off all but 1/2 inch of overhang. Fold overhang in and press, forming double-thick sides. Pierce crust all over with fork; chill 30 minutes.
Preheat oven to 400°F. Line crust with foil; fill with dried beans or pie weights. Bake 20 minutes. Remove foil and beans. Bake until golden, pressing with back of fork if crust bubbles, about 20 minutes longer. Cool completely.
Stir 1 cup sugar and 1/4 cup water in heavy large saucepan over low heat until sugar dissolves. Increase heat. Bring to boil, brushing down sides of pan with wet pastry brush. Boil without stirring until deep amber color, swirling pan occasionally, about 8 minutes. Remove from heat; add cream (mixture will bubble up). Return pan to low heat; whisk caramel until smooth. Add butter, honey, and vanilla. Whisk until sauce thickens slightly, about 3 minutes. Remove from heat. Add all chocolate; whisk until smooth. Stir in nuts. Spread filling in crust. Chill tart until firm, at least 3 hours or overnight. Serve with ice cream.