Preheat oven to 350 degrees F. Lightly grease 2 cookie sheets and set aside.
Melt chocolate in a double boiler set over barely simmering water or in the microwave at 50 percent power. Allow to cool to room temperature.
In a mixer, beat the butter and sugar until smooth, about 3 minutes. Add the eggs 1 at a time, beating well after each egg is added. Beat in the vanilla and the espresso. Gradually add the flour, beating well after each addition until just combined and scraping down the sides of the bowl, as necessary. Add baking soda and salt. Mix in the melted chocolate and then the nuts. Drop the batter by 2 tablespoons onto the greased cookie sheets, leaving 2 inches between each cookie. Bake until soft and lightly crisped around the edges, about 12 minutes, rotating pans halfway through cooking. Cool on wire racks.
A viewer or guest of the show, who may not be a professional cook, provided this recipe. It has not been tested for home use.