Combine all-purpose flour, baking powder, baking soda, and salt. Set aside.
In a 1 quart wide mouth canning jar, layer dark brown sugar, white sugar, cocoa, chopped pecans, and chocolate chips. Pack everything down firmly before you add flour mixture, it will be a snug fit.
Attach a tag with the following instructions: Chocolate Cookie Mix in a Jar: 1. Preheat oven to 350 degrees F (175 degrees C) 2. Empty cookie mix into large bowl. Thoroughly blend mixture with hands. Mix in 3/4 cup softened butter or margarine, 1 egg, slightly beaten, and 1 teaspoon vanilla. Shape into walnut size balls, and place 2 inches apart on a parchment lined baking sheet. 3. Bake for 11 to 13 minutes. Cool 5 minutes on baking sheet, then move to wire racks.