Heat the oven to 180C/160C fan/gas 4. Butter a 23cm springform cake tin and dust with flour. Beat the softened butter with 115g of the sugar and a pinch of salt for 3-5 mins until pale and creamy. Add the vanilla extract, lemon zest and juice and mix until combined.

Separate the eggs, putting the egg whites in a large mixing bowl. Use an electric hand mixer to beat the whites with the remaining sugar until stiff peaks form. Mix the egg yolks into the butter and sugar mixture.

Mix the flour with the baking powder and cornflour, then tip into the butter, sugar and yolk mixture. Mix to combine, then stir in the milk followed by a spoonful of the egg whites. Once that is fully incorporated, gently fold the remaining egg whites into the batter.

Spoon the batter into the springform pan. Press the apples into the batter cut side down and bake for 45-50 mins until golden and a skewer inserted into the centre comes out clean. Leave to cool in the tin for a while, then transfer to a cooling rack. Dust with icing sugar. Will keep in an airtight container for up to three days.