Spray a piece of parchment or waxed paper with nonstick spray. Spread the Nutella on the greased paper in a rectangular shape- about ½-inch thick. Place it in the freezer on a flat surface until it is frozen solid.
Preheat the oven to 350 degrees F. Line two cookie sheets with parchment paper or silpat mats.
Sift together the flour and baking soda. Set it aside.
In a large bowl, use an electric mixer to combine the butter and sugars. Beat in the pudding mix until blended. Stir in the eggs and vanilla, and then the dry ingredients.
Take the Nutella out of the freezer. Peel off the paper and put it on a cutting board. Use a sharp knife to carefully cut the Nutella into chunks. Stir about 3/4 of the Nutella chunks into the cookie dough, and save some chunks to place on top of the cookies.
Use a cookie scoop or rounded spoonful to place little balls of cookie dough on the prepared cookie sheets. Top each ball of cookie dough with a couple of chunks of Nutella. If you have any leftover cookie dough or Nutella chunks, place them in the refrigerator while your first batch is baking.
Bake 12 to 14 minutes, or until the cookies are golden and not so soft in the middles. The edges should be golden brown. Remove them from the oven and let them cool on the cookie sheets for about 10 minutes before moving them to a wire rack to cool completely. Repeat with the remaining chilled cookie dough.