1. Heat oven to 375 degrees F. In a medium-size bowl, whisk together flour, baking soda and salt. Set aside.
2. In large bowl, beat together butter and peanut butter with an electric mixer until smooth. Beat in both kinds of sugar until pale-colored. Add eggs and vanilla, beating until smooth. On low speed, beat in flour mixture just until combined, or, alternately, stir in by hand. Add chocolate chunks and stir until evenly distributed.
3. Using a small scoop, form mounds of cookie dough on a large cookie sheet (about 12). Press down with a fork in a crosshatch pattern. Bake at 375 degrees F for 15 minutes or until browned. Cool on wire rack; repeat with all dough.