Make brownies per the box directions. Pour into a 13x9 inch baking pan and bake per box directions 20-25 minutes or until toothpick inserted near the center comes out clean. Cool on wire rack.
In a large bowl, whisk milk and pudding mix for 2 minutes. Let stand for 2 minutes or until soft-set. Spread over filling. Refrigerate for 1 hour or until served.
Cut into squares, garnish with whipped topping and nuts , if desired. ( my kids won't eat it if nuts are in it, but walnuts would be a great addition.
This would make a great make-ahead dessert to take to family or church gatherings or office potlucks.