Preheat the oven to 350°F (175°C).

In a bowl, mix 180 grams of Nutella with the egg until well combined. Add the flour and mix briefly until just combined. Form the dough into balls (about 1 ounce or 30 grams each) and place them on a baking sheet. Make a small indentation in the center of each ball (you can use your finger or the handle of a wooden spoon).

Bake for 10-12 minutes, then remove from the oven and let cool.

Once cooled, use a piping bag to fill the indentations with the remaining Nutella and serve.