Preheat oven to 180°C. Line 2 baking trays with baking paper.
Cream the butter and sugar and beat until the mixture is light and fluffy.
Sift in the flour and bring the mixture together to form a dough (don't overbeat).
Roll the dough into balls and place them a few centimeters apart on a lined baking tray.
Gently flatten the balls out slightly with your hand. Using your thumb make a dent in the middle of each cookie (don't make a hole through to the bottom though!)
Fill each hole with Nutella.
Bake for 15 minutes or until light golden brown.