Preheat oven to 350°
In a medium sized bowl, mix butter, sugars, eggs, oil and vanilla until well combined.
In a separate bowl, lightly mix flour, salt, cocoa powder and espresso powder.
Add the dry ingredients to the wet ingredients a little at a time until just combined. Do not overmix!
Gently fold in chocolate chips.
Spread into a greased 8x8 pan.
Evenly drop nutella by teaspoons over the batter.
Using a butter knife, gently swirl (do not stir) the nutella into the brownie batter.
Bake for 20-25 minutes or until set. **Note that if you insert a toothpick it will not come out completely clean due to all of the chocolate!
Allow to cool for at least 10 minutes before cutting and serving.