Ingredients

  • 28 chocolate wafers such as Nabisco Famous, finely ground in a food processor (1 1/2 cups)
  • 3/4 stick (6 tablespoons) unsalted butter, melted and cooled completely
  • 1/2 lb fine-quality bittersweet chocolate (no more than 60% cacao if marked), coarsely chopped
  • 3/4 stick (6 tablespoons) unsalted butter, cut into 1/2-inch cubes
  • 2 large eggs, lightly beaten
  • 1/2 cup heavy cream
  • 1/4 cup granulated sugar
  • 1/4 teaspoon salt
  • 1 teaspoon pure vanilla extract
  • Garnish: unsweetened cocoa powder for sprinkling
  • an 8-inch (20-cm) round springform pan

Method

  • Put oven rack in middle position and preheat oven to 350°F. Wrap a sheet of foil over bottom of springform pan (in case of leaks). Lightly butter side of pan.
  • Stir together ground wafers and butter in a bowl until combined, then pat mixture evenly onto bottom of pan and 1 1/2 inches up side. Bake until crust is slightly puffed, about 10 minutes, then cool completely in pan on a rack, about 15 minutes. Leave oven on.
  • Melt chocolate and butter in a 2-quart heavy saucepan over low heat, stirring until smooth, then remove from heat and cool 5 minutes.
  • Whisk together eggs, cream, sugar, salt, and vanilla in a bowl. Whisk chocolate mixture into egg mixture until combined well.
  • Pour filling into cooled crust and rap pan once on counter to eliminate any air bubbles. Bake until filling 1 inch from edge is set and slightly puffed but center trembles slightly when pan is gently shaken, 20 to 25 minutes. (Center will continue to set as it cools.)
  • Cool tart completely in pan on a rack, about 2 hours. Chill, uncovered, until center is firm, about 4 hours. Remove side of pan and sprinkle with cocoa to serve.