Add the softened butter and sugar to a bowl and beat and cream together.

Then add in the egg and vanilla extract and beat again.

Next, add the plain flour, baking powder, and bicarbonate of soda and mix well until a cookie dough is formed.

Add in the chopped dairy milk and crushed smarties egg and combine.

Roll the dough into even sized cookie dough balls and place on a lined baking tray (I used 2 trays so they we nice and spread out) and place in the freezer for 30 mins. Preheat the oven to 200°c.

Remove from the freezer and bake in the oven for 12-14 mins. Once cooked remove from the oven and leave to cool for at least 30 mins before tucking in.