Preheat the oven to 180°C.
Place the sponge base into a 23cm springform tin and drizzle with liqueur.
Whisk sugar, lemon juice, lemon zest, and cornflour in a bowl.
Beat in the cream cheese, followed by eggs added one at a time.
Mix in vanilla seeds and double cream until smooth.
Fold in raspberries and white chocolate then pour into the tin.
Place the tin into a roasting tray containing 0.5cm of water.
Bake for 50 minutes until golden and set, then cool in the tin.
Stir-fry 250g of raspberries in a hot pan for one minute.
Add liqueur to the pan and carefully flambé.
Stir in lemon juice and icing sugar to taste.
Blend the mixture and pass through a sieve to remove seeds.
Serve cheesecake wedges with whole raspberries, berry sauce, and whipped cream.