Preheat the oven to 180°C.
Place the sponge base into a 23cm springform cake tin.
Whisk the sugar, lemon juice, lemon zest, and cornflour in a bowl.
Beat in the cream cheese, followed by the eggs one at a time.
Mix in the vanilla seeds and double cream until smooth.
Fold in the strawberries and white chocolate.
Pour the mixture into the tin and distribute it evenly.
Wrap the tin in foil and place it in a roasting tin with 0.5cm of water.
Bake for 50 minutes until golden and just set.
Cool in the tin then refrigerate until ready to serve.
Stir-fry sauce strawberries in a hot pan for one minute.
Mix in the lemon juice and icing sugar to taste.
Blend the mixture and sieve to remove seeds.
Serve slices topped with sauce and fresh strawberries.