Preheat your oven to 325°F. Grease a 10-inch skillet and set it aside.

In a stand mixer, beat the eggs and sugar until the mixture becomes thick and light yellow (about 5 minutes).

Add cocoa powder, instant espresso, flour, and salt. Mix until just combined.

Turn the mixer to low, and slowly pour in the melted, cooled butter and Nutella. Keep mixing until no streaks remain.

Gently fold in the chocolate pieces.

Pour the batter into the skillet and bake for 25 minutes, or until the brownie is puffed on top but still a bit wiggly in the center. Remember, the longer it bakes, the more set the center will be.

Take the skillet out of the oven and let it cool slightly.

Serve it warm, topped with a scoop of vanilla ice cream if you like.