Like brownies, these cookies are dense and fudgy beneath their crackly exteriors. Use your favorite nuts in place of the walnuts, or omit them altogether. The dough can be shaped into balls and refrigerated for up to two days or frozen for up to three weeks; freeze on a baking sheet until firm, then transfer to a resealable plastic bag.

　　

Ingredients

makes about 30

　　9 ounces semisweet chocolate, chopped into 1/4-inch chunks

　　3 ounces unsweetened chocolate, coarsely chopped

　　6 tablespoons unsalted butter

　　1 cup sugar

　　3 large eggs

　　1/2 teaspoon pure vanilla extract

　　1 cup sifted all-purpose flour

　　1/4 teaspoon salt

　　3/4 cup (about 3 ounces) chopped walnuts (optional)

　　

Step 1

Preheat the oven to 375°F. Line two large baking sheets with parchment paper; set aside. In a heatproof bowl set over (but not touching) simmering water, melt 5 ounces semisweet chocolate, the unsweetened chocolate, and the butter. Stir until smooth. Set mixture aside to cool slightly, about 5 minutes.

　　

Step 2

In the bowl of an electric mixer fitted with the paddle attachment, beat chocolate mixture and sugar on medium speed until well combined, about 3 minutes, scraping down the sides of the bowl as needed. Add eggs, and mix until completely combined. Beat in vanilla. Add the flour and salt, and beat until just incorporated. Stir in remaining 4 ounces semisweet chocolate and the nuts, if using.

　　

Step 3

Shape 2 tablespoons of dough at a time into 1 1/2-inch balls and place about 1 1/2 inches apart on prepared baking sheets. Bake, rotating sheets halfway through, until edges are set and centers are still a bit soft, 9 to 11 minutes. Transfer parchment and cookies to a wire rack to cool completely. Cookies can be kept in an airtight container at room temperature for up to 4 days.

　　Reprinted with permission from Martha Stewart's Baking Handbook by Martha Stewart. © 2005 Clarkson Potter