This rich chocolate filling is welcome as a thin layer in a tart as opposed to a deep cake or torte. The decoration may be as simple or complex as you wish.

Makes one 10-inch tart, about 8 servings


Crust

1 cup all-purpose flour
3 tablespoons alkalized (Dutch process) cocoa
1/4 cup sugar
1/4 teaspoon salt
3/4 teaspoon baking powder
5 tablespoons unsalted butter, cold
1 large egg

Filling

1/2 cup sugar
1/3 cup water
4 tablespoons unsalted butter
8 ounces bittersweet chocolate, cut into 1/4-inch pieces
3 eggs
1 cup (about 9 ounces) mascarpone cheese


2 ounces milk or white chocolate, melted

One 10-inch tart pan with removable bottom

  1. For the crust, combine dry ingredients in the bowl of a food processor fitted with the metal blade. Pulse to mix. Cut butter into 10 pieces, add to work bowl, and pulse until finely mixed in. Add egg and pulse until dough forms a ball. Wrap and chill dough until ready to bake the tart.
  2. Preheat oven to 350 degrees and set a rack in the lowest level. Knead chilled dough slightly until malleable, then form into a disk. Flour dough and surface and roll dough to fit pan. Sever excess dough at rim of pan and press dough firmly into pan.
  3. For the filling, bring sugar and water to a boil in a non-reactive saucepan. Add butter and continue to cook until butter is melted. Off heat, add chocolate and allow to stand 2 minutes, then whisk smooth.
  4. Whisk together the eggs and mascarpone, then whisk in the chocolate mixture. Pour the filling into the crust and bake until the dough is baked through and the filling is set, about 30 minutes.
  5. Cool the tart on a rack.
  6. To decorate the tart, fill a non-pleated plastic bag a with the melted chocolate. Force all the chocolate into one corner of the bag and snip a hole in the end. Streak the top of the tart with the chocolate.