from: Fine Cooking Magazine, No. 92
1/4 tsp. table salt
12 Tbs.cold, butter,cut into pieces
1/2 tsp vanilla
1 lb. semisweet or bittersweet chocolate, coarsely chopped
3/4 cup 2% milk
8 Tbs. butter, cut in pieces
4 large eggs
2/3 cup granulated sugar
2 Tbs. Kahlúa, Amaretto, Grand Marnier or Frangelico
Position an oven rack in the center of the oven and heat the oven to 350°F. Line the bottom and sides of a 9x13-inch baking pan with foil, allowing foil to overhang the long sides of the pan. Lightly butter the foil.
In a food processor, combine the flour, confectioners’ sugar, and salt. Process the ingredients briefly to combine. Scatter the cold butter pieces and the vanilla over the flour mixture and process, using short pulses, until the dough begins to form small clumps. Turn the dough into the prepared pan. Using lightly floured fingertips, press the dough into the pan in a smooth, even layer. Bake until pale golden, especially around the edges, 22 to 25 minutes. Do not overbake or the crust will be hard and crispy. Transfer the pan to a cooling rack and lower the oven temperature to 325°F.
In a medium bowl, melt the chocolate, milk, and butter together in the microwave. Whisk until smooth and set aside to cool slightly.
In a stand mixer fitted with a paddle attachment or in a large mixing bowl, beat the eggs, sugar, and liqueur on medium-high speed until foamy and lighter in color, 2 minutes. Reduce the speed to low and gradually add the chocolate mixture. Stop the mixer and scrape down the bowl and beater. Beat on medium speed until well blended, about 30 seconds.
Pour the chocolate batter over the baked crust and spread evenly. Bake until the sides are slightly puffed and a toothpick inserted near the center comes out wet and gooey but not liquid, 30 to 35 minutes. Transfer the pan to a rack.
When completely cool, cover with plastic and refrigerate until very cold, at least 12 hours or up to 2 days. To serve, using the foil as handles, lift the rectangle from the pan and set it on a cutting board. Tipping the rectangle, carefully peel away the foil. Using a hot knife, cut into triangles.