170g1-1/2 sticks cold unsalted butter, cut into 1/2-inch cubes
50g1/4 cup cold vegetable shortening or non-butter flavored margarine
1/2teaspoonsalt
7 to 9tablespoonsice water
For the filling:
1/2cupgolden raisins
1cupwater
2lbgreen Swiss chardhalf of the center ribs chopped fine
1large egg
1/2cupheavy cream
1 1/2tablespoonsgranulated sugar
1/2teaspoonfinely grated fresh orange zest
1/3cuppine nutstoasted
2teaspoonsicingconfectioners sugar
Instructions
For the pastry:
Blend together flour, butter, shortening, and salt in a bowl with your fingertips or a pastry blender (or pulse in a food processor) just until mixture resembles coarse meal with some small (roughly pea-size) butter lumps. Drizzle 5 tablespoons ice water evenly over mixture. Gently stir with a fork (or pulse) until incorporated.
Squeeze a small handful of dough: If it doesn't hold together, add more ice water, 1/2 tablespoon at a time, stirring (or pulsing) until incorporated. Do not overwork dough, or pastry will be tough.
Turn dough out onto a work surface. Gather all dough together with pastry scraper.divide dough with one half slightly larger, then form each into a ball and flatten each into a 5-inch disk. Wrap each disk in plastic wrap and chill until firm, at least 1 hour. Dough can be chilled up to 2 days ahead.
For the filling:
Bring raisins and water to a boil in a heavy saucepan, then remove from heat and let stand, covered, 1 hour. Drain in a colander, then pat dry with paper towels. Put oven rack in middle position and preheat oven to 200C (400F).
Blanch chard in a large pot of boiling salted water, uncovered, stirring occasionally, until tender but still bright green, about 5 minutes. Transfer chard with a slotted spoon to a large bowl of ice and cold water to stop cooking. Drain chard in a colander, then squeeze out excess water by handfuls. Coarsely chop chard.
Whisk together egg, cream, granulated sugar, zest, and a pinch of salt in a large bowl. Stir in pine nuts, raisins, and chard until combined.
For the Tourte de Blette:
Roll out larger piece of dough on a lightly floured surface with a lightly floured rolling pin into a 38- by 27-centimeter (15- by 11-inch) rectangle and fit into tart pan (do not trim edges). Chill shell while rolling out top.
Roll out smaller piece of dough on a lightly floured surface with lightly floured rolling pin into a 30- by 22-centimeter (12- by 9-inch) rectangle. Spread chard filling evenly into shell, then top with second rectangle of dough. Using a rolling pin, roll over edges of pan to seal tart and trim edges, discarding scraps. Cut 3 steam vents in top crust with a paring knife, then put tart in pan on a baking sheet. Bake until top is golden, about 1 hour. Transfer to a rack and cool 10 minutes, then remove side of pan. Cool to room temperature, about 1 hour. Dust with confectioners sugar.