Place biscuits in a food processor and crush until the texture of breadcrumbs.
Mix with the melted butter, press into a well-greased 20cm springform pan and bake for 5 minutes. Set aside to cool while making filling.
Using an electric beater, beat the cream cheese, caster sugar, plain flour, vanilla, sour cream, eggs and extra yolk until light and fluffy.
Using a spatula, gently fold in half the raspberries and pour over the top of the biscuit base.
Bake for 40 minutes and then check. Cheesecake should be set but slightly wobbly in the middle. If it appears too runny after this time, continue to bake and check every 5 minutes. Leave in the pan to cool.
Place the remaining raspberries into a saucepan with the icing sugar and raspberry jam. Heat until the juice starts to come out of the fruit and is slightly thick.
Remove from heat and then mash with a fork or potato masher.
Sieve the raspberry mixture, then pour over the cheesecake in pan and refrigerate for at least 4 hours.