Place the butter and both sugars into a bowl and beat well until you get a creamy mixture.
Meanwhile place the hazelnuts in a sealed plastic bag and bash up gently with a rolling pin to create small chunks of nut.
Once you have beaten the butter and sugars together, beat in the vanilla extract and the egg, mixing well to combine.
Add the flour, bicarbonate of soda and salt to the bowl and continue to mix well until you have a rough dough.
Add the milk chocolate chips and hazelnuts to the dough and mix until you have a well combined dough.
Pull together small golf ball sized balls of the cookie dough and place these on a tray lined with baking parchment. Space the cookies well apart as they will spread in the oven. However do not flatten out the balls of dough.
Once you have shaped all the cookies, you should get 25-30 cookies from this mix, place the trays in an oven at 170CFan. Bake the cookies for 10 minutes, they should be a little soft in the middle.
Remove the cookies from the oven, place them on a wire cooling rack and allow to cool. Once cool store in an airtight container.
This basic cookie dough recipe can be easily adapted for other flavours.For anyone with a nut allergy, simply leave out the hazelnuts and increase the chocolate chips to 200g.