Preheat oven to 375°F (190° C). Combine flour, baking soda and salt in medium bowl; set aside.
Mix Becel® Original margarine with sugars in large bowl. Mix in eggs and vanilla until blended. Gradually add in flour mixture; mix until blended. Stir in cocoa powder. Drop by tablespoonfuls on ungreased baking sheets, 2-in. (5 cm) apart. Flatten slightly, then top with 3 chocolate chunks.
Bake 7 minutes or until edges are set. Cool 2 minutes on wire rack; remove cookies from sheets and cool completely.