|Plain flour||3 Ounce (75 Gram)|
|Baking powder||1 Pinch|
|Caster sugar||5 Ounce (150 Gram)|
|Vegetable oil||1 Tablespoon (For Greasing)|
|Double cream/Whipping cream||1⁄2 Pint (300 Milliliter)|
|Icing sugar||2 Teaspoon, sifted|
|Seedless grapes/Black grapes, halved and seeded||9 Ounce, halved, (250 Gram)|
|Ratafia biscuits||10 , crushed|
1. Heat the oven to 190C/375F/Gas 5. Grease a 33 x 23 cm/13 x 9 inch Swiss roll tin; line tin with greaseproof paper and grease paper.
2. Sift the flour with the salt and baking powder and set aside.
3. Put the eggs and sugar into a large heatproof bowl. Set the bowl over a pan half full of gently simmering water. Using a rotary or hand-held electric whisk, beat the mixture until thick and foamy. Continue beating until the mixture is thick enough to hold the trail of the whisk for about 3 seconds when beaters are lifted.
4. Remove the bowl from the pan and beat for a few minutes more until the mixture is cool. Using a large metal spoon, fold in the sifted flour, one-third at a time.
5. Pour mixture into the prepared baking tin and spread evenly by gently tilting the tin. Bake the cake immediately in the oven for 15-20 minutes until the surface is golden and springy to the touch. Leave to stand in the tin for 1-2 seconds, then turn out on to a wire rack. Peel off the lining paper and leave to cool completely.
6. Make filling: whip cream in a bowl with kirsch and sugar until standing in soft peaks. Spoon half the whipped cream into another bowl and fold in three-quarters of the prepared grapes.
7. Assemble gateau: cut sponge across into 3 equal rectangles, then sandwich them together with the grape cream in between. Spread three-quarters of the remaining whipped cream over the top and sides. Transfer to a serving plate.
8. Using a palette knife, press the crushed ratafias over the sides of the gateau. Put the remaining cream into a piping bag fitted with a large star nozzle and pipe a border around the top edge. Decorate with the remaining grapes and the ratafias, if liked. Keep in a cool place and serve within 2 hours.