Preparation Preheat oven to 375°F. Whisk flour, cocoa, and salt in small bowl to blend. Coarsely chop 1 1/2 cups chocolate chips in processor. With machine running, add butter, then 1/2 cup sugar through feed tube. Add egg yolk and both extracts and process to blend. Using on/off turns, mix in walnuts, scraping down sides of bowl occasionally. Add flour mixture and process just until dough comes together, about 1 minute. Transfer dough to large bowl. Using hands, mix in remaining 1/2 cup chocolate chips. Using 1 tablespoon dough for each, shape dough into 1 1/4-inch-diameter balls. Press each dough ball to 1/2-inch thickness; dip 1 side into remaining 1/2 cup sugar to coat. Arrange cookies, sugar side up, on 2 ungreased baking sheets. Bake cookies until set and almost firm to touch, about 18 minutes; cool on racks.
Preparation Preheat oven to 375°F. Whisk flour, cocoa, and salt in small bowl to blend. Coarsely chop 1 1/2 cups chocolate chips in processor. With machine running, add butter, then 1/2 cup sugar through feed tube. Add egg yolk and both extracts and process to blend. Using on/off turns, mix in walnuts, scraping down sides of bowl occasionally. Add flour mixture and process just until dough comes together, about 1 minute. Transfer dough to large bowl. Using hands, mix in remaining 1/2 cup chocolate chips. Using 1 tablespoon dough for each, shape dough into 1 1/4-inch-diameter balls. Press each dough ball to 1/2-inch thickness; dip 1 side into remaining 1/2 cup sugar to coat. Arrange cookies, sugar side up, on 2 ungreased baking sheets. Bake cookies until set and almost firm to touch, about 18 minutes; cool on racks.