Preheat oven to 325 degrees F.
Line a 13x9" baking pan with nonstick foil.
Beat butter and sugar until creamy.
Add powdered sugar and vanilla.
Add flour to form your dough.
Press half in the bottom of the pan.
Add chips to rest of the dough and chill.
Bake the crust for 15-20 minutes.
Remove from the oven and let cool a few mins.
Gently pour on the Nutella and spread very gently.
Crumble the rest of the dough on top.
Bake 25-30 minutes. Middle may be jiggly still.
Remove and cool.
Cut into bars!
Drizzle with more Nutella, if desired.