The hazelnut spread helps keep the cookies soft and fudgy, but most of the hazelnut flavor comes from the hazelnuts. You could also bump up the flavor by using chunks of hazelnut flavored chocolate rather than bittersweet chips.
Preheat oven to 350 degrees. Line two cookie sheets with parchment paper.
Mix together flour, cocoa powder, baking powder and salt. Set aside.
Cream the butter with the Nutella and both sugars. Beat in the eggs and vanilla. Add the flour mixture and stir until it is incorporated, then stir the chocolate chips and hazelnuts. Drop by tablespoons onto cookie sheets and bake for 10-12 minutes. Cool on cookie sheet for a few minutes then transfer to a wire rack to cool.