Preheat the oven to 350 F. Melt the butter in the cast iron skillet (or non-stick, oven-proof skillet) on top of stove on medium-low heat. I used an 8 inch cast iron skillet. In a small bowl, combine the flour and cocoa powder. When the butter has melted, pour it into a medium sized metal mixing bowl. Add the sugar to the melted butter and beat until combines. Next, beat the eggs, vanilla, and salt into the butter mixture until smooth. Mix in the flour/cocoa powder mixture. Fold in the 3 tablespoons of Nutella. Refrain from eating the Nutella off the measuring spoons.

Spread the batter into the cast iron skillet and bake for about 30-40 minutes.