For the sponge:4 egg yolks½ cup oil½ cup boiling water1 teaspoon vanilla essenceBeat until combined.Then sift the following over1¼ cups cake flour2 teaspoon baking powder2 tablespoon cocoa powder1 cup castor sugarPinch saltBeat everything together until smoothIn a clean glass bowl beat 4 egg whites with ½ teaspoon baking powder until stiff peaks form. You should be able to turn the bowl over and whites shouldn't fall out.Fold into the above mixture. Pour into a greased swiss roll pan and bake for 12 minutes.Turn out on to a wire rack cool completly.Cut the cool cake in half.Beat ¾ cup fresh cream until stiff. Spread evenly over one half of the cake sandwich with the other half. Leave in the fridge for 30 minutes to firm before cutting.Cut into equal size fingers.Put fingers in the freezer before coating. In the meantime over a double boiler melt 2 x 150g Cadbury dairy milk chocolateWhen melted completely break in 2 x 100g Lindt excellence dark or mild dark chocolate. Allow to melt in the hot chocolate mixing with a spetula.Dip each finger coating well.