Preheat the oven at 180°C. Grease the sides and base of 8-inch springform pan with butter and line the base with parchment paper.
In a food processor, pulse the cookies into crumbs. In a small bowl mix the crumbs and melted butter. Pour the mixture into the base of the pan, and evenly spread. Bake for 10 minutes, and let cool. Reduce the oven to 150°C
Filling
Place white chocolate in a heat proof bowl. Fill a saucepan with a couple inches of water, on medium heat bring the liquid to a simmer. Turn off heat, place the bowl with chocolate over the saucepan and allow the chocolate to melt. Stir the chocolate until smooth. Alternatively, Melt the white chocolate in the microwave in 30 second intervals and mix, until the chocolate has fully melted and has a smooth consistency.
In a large bowl, with a hand whisk combine cream cheese and sugar. Add heavy cream and mix until the mixture is smooth. Add the cornstarch and mix well until fully combined. Add the vanilla essence and mix until well combined. Add the egg, one at a time, mixing well after each addition to ensure that it is fully combined and smooth.
Add the melted chocolate and with a spatula fold in the ingredients until fully combined and smooth.
Pour the cheesecake filling into the slightly cooled cheesecake base. Bake for 55 to 60 minutes, or until the sides are set and the Centre is slightly wobbly. Turn off the oven, keep the oven door ajar and allow the cheesecake to cool to room temperature inside the oven. (This prevents the cheesecake surface from cracking)
Allow the cheesecake to rest in the fridge for 3-4 hours, or ideally overnight.
Run the knife around the rim of the pan to loosen the cake, and allow it to cool for at least 2 hours before removing the rim of the pan. Let set for 6 hours or overnight.
Topping
In a small saucepan, cook the frozen raspberries, sugar and lemon juice on medium-high heat for 5 - 7 minutes. Press the berries through a strainer, reserve the liquid in the bowl and discard the seeds. Return the raspberry juice back to the saucepan and continue to cook on medium heat for an additional 5 – 7 minutes, or until it reduces to a thick syrup. Remove from heat and allow to fully cool.
In a small bowl mix the cooled raspberry reduction with the fresh raspberries, gently stir until the raspberries are fully coated with the reduction.
Assembly
Once the cheesecake is fully chilled, remove it from the springform pan and place on a serving plate. Gently arrange the raspberry topping over the cheesecake. Refrigerate until you are ready to serve.