1 1/2 tablespoons butter
2 ounces bittersweet chocolate, coarsely chopped
2 ounces unsweetened chocolate, coarsely chopped
1 tablespoon espresso powder
1 teaspoon vanilla extract
1 1/2 cups all-purpose flour (about 6 3/4 ounces)
1/2 cup unsweetened cocoa
2 teaspoons baking powder
1/8 teaspoon salt
2 1/2 cups sugar
3 large eggs
1/2 cup chopped walnuts
1/4 cup semisweet chocolate chips
1/4 cup white chocolate chips

Preparation
Preheat oven to 350°.
Place butter, bittersweet chocolate, and unsweetened chocolate into a microwave-safe bowl; microwave at HIGH 1 minute or until chocolate is almost melted. Stir until smooth. Add instant espresso powder and vanilla into chocolate mixture.

Lightly spoon flour into dry measuring cups; level with a knife. Combine flour, cocoa, baking powder, and salt, stirring well with a whisk. Combine sugar, and eggs in a large bowl; beat with a mixer at high speed 6 minutes or until thick and pale. Gently stir 1/4 of egg mixture into chocolate mixture; stir chocolate mixture into remaining egg mixture. Stir in flour mixture, nuts, and chocolate chips.

Cover baking sheets with parchment paper. Drop dough by rounded tablespoonfuls 2 inches apart on prepared baking sheets; with moist hands, gently press dough into 1/4-inch-thick rounds. Bake at 350° for 15 minutes or until set. Cool 1 minute. Remove from pans; cool completely on wire racks.