Mix brownie according to instructions. Grease 18 muffin tins.
Preheat oven to 350°F. Scoop batter into each muffin tin about 1/3 full. Add a generous dollop of nutella in the middle of each muffin tin (about 1 tsp). Add more brownie batter on top, until each muffin tin is about 2/3 full.
Bake about 20 minutes. A knife inserted near the side of the brownies (not where the nutella is) should come out clean.
Let muffins cool for about 5 minutes,and then use a plastic knife around the edges to loosen and remove brownies. Serve while warm.
The nutrition information provided are only estimates based on an online nutritional calculator. This is not a comprehensive list of all the nutrients in the recipe (i.e., does not include vitamins, cholesterol, etc). I am not a certified nutritionist. Please consult a nutritionist or doctor for accurate information and any dietary restrictions and concerns you may have.