Line 8-inch square pan with foil, with ends of foil extending over sides. Microwave first 3 ingredients in large microwaveable bowl on HIGH 2 min.; stir until chocolate is completely melted and mixture is well blended.
Add dry pudding mix; stir with whisk 2 min. Gradually stir in sugar; press onto bottom of prepared pan. Top with nuts; press gently into fudge to secure.
Refrigerate 2 hours or until firm. Use foil handles to lift fudge from pan before cutting into pieces.
The last cup of powdered sugar can be hard to stir in. Feel free to use clean hands to "knead" it in until blended.
Store cut-up fudge between sheets of waxed paper in airtight container in refrigerator up to 2 weeks.
* Percent Daily Values are based on a 2,000 calorie diet.
* Nutrition information is estimated based on the ingredients and cooking instructions as described in each recipe and is intended to be used for informational purposes only. Please note that nutrition details may vary based on methods of preparation, origin and freshness of ingredients used.