Preheat the oven to 180 C and line a 12 hole muffin pan with cupcake liners.
In a medium bowl, mix together the Nutella, eggs, flour and salt until combined.
Divide the batter evenly between the 12 muffin holes. If using, sprinkle each brownie cup with a few chocolate chips.
Bake for 12 minutes. Makes 12 Nutella brownie cups.
I would say baking time is pretty much depends on the oven. So try the stick test.