In a large bowl, mix together the flour, butter, sugar, egg, vanilla, water and salt. Blend briefly until all the ingredients are combined . Roll the mixture into a ball and let the dough rest in the fridge for 1 hour.

After 1 hour, take the dough out of the fridge. Place half the dough between two pieces of parchment paper and roll it out to a thickness of roughly 3mm. Repeat with the other half. Let both sheets of dough rest in the fridge for 1 to 2 hours.

Preheat the oven to 180°C.

Remove the two sheets of dough from the fridge. Using a larger diameter round cookie cutter, cut out biscuit shapes to form the cookie bases and tops. Then, using smaller musical notes cutters, cut a shape out of the middle of each top biscuit.

Bake on the middle shelf of the oven for 10 minutes. Take them out of the oven and leave to cool. Spread Nutella® on the bottom layers , then cover with the top biscuits. Enjoy!