Preparation
Preheat the oven to 220°C (200°C fan, gas 7). Separate the eggs and place the egg yolks in a mixing bowl.
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Add 4 tbsp warm water and two-thirds of the sugar.
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Blitz with a hand blender until pale and creamy.
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Whisk the egg whites with the salt, gradually adding the remaining sugar. Whisk until stiff and glossy.
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Place the beaten white eggs onto the egg yolk mixture and fold in. Sieve in the flour and cornflour.
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Carefully fold in with the spatula.
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Pour the mixture onto a baking sheet (30 x 40cm) lined with baking paper. Spread out evenly and bake for 10-12 minutes on the middle shelf of the oven until golden and springy.
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Sprinkle a large tea towel with sugar. Carefully turn out the sponge, lightly sprinkle the baking paper with cold water and carefully peel away from the sponge.
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Immediately roll up the sponge base tightly, using the tea towel to help, and leave to cool, seam side down.
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Carefully unroll the cooled sponge roll. Add 5-6 tbsp of jam and spread out evenly with a spatula.
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Whip the cream until stiff. Fold in the remaining jam and spread the cream over the sponge.
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Carefully re-roll the sponge using the cloth. Chill for at least 3 hours. Serve with icing sugar.
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