1Heat oven to 350ºF. Bake brownie mix as directed on box, using water, oil and eggs, in 13x9-inch pan. Cool completely, about 1 hour.
2Make pudding mix as directed on box for pudding, using milk; refrigerate. Cut brownies into 1-inch pieces. Thoroughly stir caramel topping into whipped topping.
3In 3-quart glass bowl, layer half each of the brownies, pudding, walnuts and whipped topping mixture; repeat.
4Cover and refrigerate at least 2 hours before serving but no longer than 24 hours. Store covered in refrigerator.