Chocolate chip cake

Preheat the oven to 180 ºC (350 ºF). Grease a flat 37 x 27 cm oven pan with margarine, butter or non-stick spray. Separate the eggs. Beat the yolks and castor sugar till creamy. Add the oil, water and butter and beat thoroughly. Sift the cake flour, salt, baking powder and cocoa together and add to the egg yolk mixture. Mix. Whisk the egg whites till stiff peaks are formed and fold into the cake flour mixture. Pour the batter into the prepared oven pan. Break one of the slabs of chocolate into fairly small pieces and press into the cake batter. Bake for 20-25 minutes or till a testing skewer comes out clean when inserted into the centre of the cake. Cool slightly. Break the remaining slab of chocolate into squares and melt in the microwave oven or over boiling water. Stir occasionally as the squares retain their shape when melted in the microwave. Spread the melted chocolate over the cake and cut into squares.
Makes about 40 squares.