Combine cake mix, vanilla pudding, eggs, oil and water according to cake mix package instructions. Beat until smooth and pour into 2-8 inch pans greased and floured with cooking spray. Bake at 350 for 35 minutes. Remove and cool layers.
With a stand mixer important unless you have a really strong arm beat cream cheese and sugar for 20 minutes. Add in the confectioners sugar and beat just until smooth. Fold in whipped topping, chopped pecans and grated hershey bar.
Frost cooled cake and enjoy. So good. Even better the next day. Scant means just slightly short of a cup.