In a bowl, mix together the egg and Nutella until smooth.

Add the flour and mix to incorporate.

Make 15 little balls out of the dough and place them on a baking tray lined with baking paper. Take a wooden spoon and use the back of it to make a hole in the centre of each ball.

Bake in a pre-heated oven at 180°C - 355°F for 10 minutes.

When ready, take them out of the oven and use the same wooden spoon to enlarge the holes.

Put some Nutella in a pastry bag and use it to fill the cookies.

Let them cool down and serve.