Mascarpone and Prune Tartlets

Bring prunes and Armagnac just to a simmer in a 1-quart saucepan, then let stand, covered, 1 hour.
Roll out dough into a 15-inch round (about 1/8 inch thick) on a lightly floured surface with a lightly floured rolling pin, lifting up dough occasionally and flouring surface as necessary to keep dough from sticking. Cut out 6 rounds with 5-inch cutter. Fit each round into a tartlet pan and trim edge. Chill tartlet shells 30 minutes.
Put oven rack in middle position and preheat oven to 375°F.
Drain prunes, reserving Armagnac in pan, and cut into roughly 1/4-inch pieces, then return to Armagnac. Let stand, stirring occasionally, until liquid is absorbed, about 10 minutes.
Lightly prick bottoms of tartlet shells all over with a fork, then line with foil and fill with pie weights. Transfer to a baking sheet and bake until sides are set and edges are pale golden, about 20 minutes. Carefully remove foil and weights and bake shells until golden brown, 10 to 15 minutes more. Remove from oven and increase heat to 400°F.
Meanwhile, stir together mascarpone, yolks, sugar, zest, vanilla, and salt.
Spoon 1/4 cup mascarpone mixture into each warm tartlet shell, then divide prunes evenly among tartlets. Bake tartlets until custard is pale golden and slightly puffed, about 25 minutes. Transfer tartlets to a rack and cool 10 minutes, then remove from pans (if tartlets stick to pans, gently pry side of tartlets loose with tip of a paring knife) and cool completely, about 45 minutes.