Preheat oven to 190°C / 170°C fan-forced. Use hand-held beaters to beat the Fairy and brown and caster sugars until pale and fluffy. Add the vanilla and egg and beat well. Stir through the sifted dry ingredients and mix well. Reserve 1/3 cup each of the chocolates and add remaining into the mixture. Stir to combine.
Spread the cookie dough mixture into a greased and lined 18cm x 28 cm slice tin. Scatter the reserved chocolate onto the top of the slice.
Bake in preheated oven for 25-30 minutes or until a skewer inserted into the centre comes out clean. Allow the slice to cool in the pan before slicing. Store in an airtight container until ready to serve.
Tips & Hints:
This slice can be frozen in an airtight container for up to 1 month
Make nostalgic recipes with Fairy Cooking Margarine