In large bowl, cream butter. ... frosting mix, and walnuts until well blended. Bake in ... soft tunnel of fudge, ordinary doneness tests cannot ... the "Tunnel of Fudge."
Preheat oven at 350°F. Cream ... frosting mix and walnuts until well blended. Pour batter ... has a soft fudge interior. Test for doneness after ... dry, shiny brownie-type crust.