Heat oven to 375°F. In large bowl, beat brown sugar and margarine until light and fluffy. Add vanilla and egg white; blend well.
Lightly spoon flour into measuring cup; level of. Add flour, cocoa, baking soda and salt; mix well. Stir in chocolate chips. Drop by teaspoonfuls 2 inches apart onto ungreased cookie sheets.
Bake at 375°F. for 8 to 9 minutes or until set. DO NOT OVERBAKE. Cool 1 minute; remove from cookie sheets.