Preheat oven to 350-degrees.
Liberally spray a 13 x 9 baking dish with baking spray. Set aside.
In a large bowl, whisk together the flour, baking soda, and salt. Set aside.
In the bowl of a stand mixer (or in a large mixing bowl with a hand mixer), cream the butter, brown sugar, and dry pudding until fluffy.
Add the egg, and vanilla to the sugar mixture and blend.
Gradually add the flour mixture to the wet ingredients and blend until a soft dough forms.
Press half of the dough evenly into the bottom of the prepared baking dish, Reserving the remaining dough for later.
Bake for 15 minutes, remove from the oven and cool slightly.
In a small bowl, whisk together the chocolate hazelnut spread and the sweetened condensed milk.
Use the offset spatula to evenly spread the chocolate mixture evenly over the baked cookie crust.
Sprinkle the peanut butter and semi-sweet chocolate chips evenly over the Nutella layer.
Break and crumble the reserved dough evenly over the entire surface of the cookie bars.
Top the cookie bars with the chopped nuts.
Bake for an additional 30 minutes at 350-degrees, or until the cookie bars are deeply golden brown in color.
Cool completely on a wire rack before slicing into bars.