In medium bowl, combine flour, cocoa, soda and salt. Mix well with a wire whisk. Set aside.
Blend sugars in a large bowl using an electric mixer set at medium speed. Add butter and mix to form a grainy paste, scraping down the sides of the bowl. Add eggs and vanilla, and beat at a medium speed until smooth. Add the flour mixture and chocolates, and blend at low speed until just combined. Do not over-mix. Drop by rounded tablespoons onto ungreased cookie sheets, 2 inches apart. Bake 23-25 minutes. Transfer cookies immediately to a cool, flat surface.
From the Dinner Co-op