Place the sugars and butter in a bowl and with a free standing mixer or using an electric beater, cream the butter and sugar until pale and fluffy.
Add the egg and egg yolk to the mix and beat until well incorporated.
Add the flour, salt, baking powder and bicarbonate of soda to the mix and beat slowly until just all incorporated.
Add in the chopped pistachios and the white chocolate, mix until evenly distributed between the mix.
Place the cookie dough mix into the fridge to chill slightly for at least 30 mins.