Microwave 4 of the chocolate squares, 6 TBSP of the butter and water in large microwaveable bowl on High for 2 minutes or until butter is melted, stir. Add dry pudding mix; stir until well blended.
Add powered sugar, 1 cup at a time, stirring until well blended after each addition. Press into foil lined 8 inch square pan.
Microwave remaining 4 chocolate squares and 2 TBSP butter in large microwaveable bowl on High 1 1/2 minutes or until butter is melted. Stir until chocolate is completely melted. Spread over pudding mixture. Refrigerate 2 hours or until firm.
Store cut-up fudge between sheets of wax paper in airtight container in refrigerator up to 2 weeks.