7 oz. semisweet chocolate, coarsely chopped

4 oz. unsweetened chocolate, coarsely chopped

9 T. (1 stick plus 1 T.) unsalted butter

1 T. vanilla extract

2 t. instant coffee granules

2/3 C. all-purpose flour

1/4 t. baking soda

1/4 t. salt

3 large eggs, at room temperature

1 C. granulated sugar

1/3 C. packed light brown sugar

12 oz. (about 2 C.) semisweet chocolate chips

1 1/2 C. coarsely chopped walnuts

Position a rack in the center of the oven and preheat to 350° F. Lightly butter three large, heavy baking sheets.

In the top of a double boiler set over hot, not simmering water, melt the chocolates with the butter, stirring frequently until smooth. Remove the top part of the double boiler from the bottom and cool the chocolate-butter mixture for 10 to 15 minutes, until tepid.

In a small cup, combine the vanilla and coffee. Stir until the coffee dissolves. In a medium bowl, using a wire whisk, stir together the flour, baking soda and salt.

In a large bowl, using a hand-held electric mixer set at high speed, beat the eggs, granulated sugar, and brown sugar for 5 to 7 minutes, until the mixture forms a pale thin ribbon when the beaters are lifted. At low speed, beat in the vanilla-coffee mixture until blended. Beat in the chocolate-butter mixture. Using a rubber spatula, stir in the flour mixture just until smooth. Fold in the chocolate chips and walnuts.

Drop the cookies by 1/4 cupfuls onto the prepared baking sheets (do not flatten), leaving 2 inches between cookies. Bake the cookies, one baking sheet at a time, for 9 to 12 minutes, until the tops crack and the cookies are barely firm when gently pressed with a finger. (To ensure their fudgy texture, it is better to underbake the cookies.)

Cool the cookies on the baking sheet on a wire rack for 5 minutes. Using a pancake spatula, transfer the cookies to a wire rack to cool completely. Store the cookies at room temperature in an airtight container for up to 2 days, or wrap individually in plastic wrap and freeze for up to 1 month.

Makes about 23 cookies.