Break up any large clumps; reserve 1/2 cup for topping.
Microwave chocolate and milk in large microwaveable bowl on HIGH 2 min. or until chocolate is almost melted; stir until chocolate is completely melted and mixture is well blended.
Stir in remaining nuts; spread onto bottom of 8-inch square pan.
Top with reserved nuts; press gently into fudge with back of spoon.