Preheat oven to 350°F.

In a medium-sized mixing bowl, whisk together Nutella, eggs, sugar, milk, and vanilla.

Whisk in the flour until smooth and creamy.

Grease a mini brownie or cupcake pan with baking spray.

Fill each cavity about 2/3 full with the Nutella mixture.

Bake for 14 to 15 minutes or until a toothpick comes out clean.

Invert onto a cooling rack and let cool.

Dust with powdered sugar before serving.