Place tablespoons of the hazelnut spread onto a plate lined with baking paper. Freeze for 1-2 hours until solid.
In a large bowl, mix together the butter, caster sugar and brown sugar until soft and fluffy. Then stir in the egg and the vanilla extract.
Mix in the flour then use your hands to press everything together into a ball of dough.
Pour the chopped Kinder chocolate into the bowl and use your hands to press it into the dough.
Divide the dough into 6 equal pieces and roll each piece into a ball.
Use your thumb to make a small dent in each ball, fill with a frozen tablespoon of hazelnut spread, then wrap the dough round to cover it completely.
Place the dough balls onto a lined baking tray and freeze for 1 more hour. In the meantime, preheat your oven to 200°C (180℃ for fan ovens).
Bake for 12-15 minutes until the cookies are very slightly golden on top. You can use an extra large cookie cutter to reshape the cookies while they're still warm if you want a more precise shape.
Let the cookies cool completely on the tray then top with more hazelnut spread and Kinder Bueno pieces. Enjoy!