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Prepare two sponge baking pans measuring 20cm round. Grease the sides and line the base with baking/parchment paper. Cover a wire baking rack with parchment paper. Add the butter, vanilla extract and sugar to the mixing bowl. Beat until the mixture becomes fluffy and light. Beat them into the mixture. Then beat in the milk. Stir in each batch of flour thoroughly. Divide the batter evenly. Bake for 30 minutes. Tip the two halves out onto the wire rack to cool. Turn them over to have the top side facing upward before leaving to cool. Spread the jam over the top of one half once cooled. Place the other half onto the jam covering to sandwich the two together. If you like, whipped cream can also be piped on top of the jam. If wished, you can dust with icing sugar to complete the look. Cut into slices for serving.
Preheat the oven to 180C/350F. Use an electric mixer to beat the ingredients. Add the eggs one at a time. Add the sifted flour, a half amount at a time. Transfer the sponge cake batter to each pan. Place the cake pans into the oven. Remove from the oven. Transfer the base half to a serving plate. Serve.