Preheat the oven to 350F degrees and position the oven rack on the bottom 1/3 of the oven.
Wrap the outside of 9-inch springform pan with aluminum foil so that the bottom and sides are covered. Wrap at least 3 times so that every part of the outside of the pan is tightly covered.
Pulse the cookies in a food processor* until they're fine crumbs.
Add in the melted butter and pulse a few more times to combine.
Press the mixture into the bottom of the prepared pan and slightly up the sides to form a little edge.
Bake in the preheated oven for 8 minutes. (Remove from the oven but leave it turned on).
White Chocolate Cheesecake Filling
Chop the white chocolate into very small pieces and place in a large, glass bowl. Microwave for 30-second intervals on medium power (NOT high power/regular power or the chocolate will burn), stirring in between each interval, until melted.
In a large bowl beat the cream cheese until soft. Beat in the sugar and vanilla extract.
Beat in the slightly cooled white chocolate, turning off the mixer and scraping down the sides of the bowl as necessary.
Beat in the sour cream and cornstarch. Then beat in the eggs 1 at a time until just combined.
Place the springform pan into the center of a large roasting pan. Pour boiling water into the roasting pan so that there's about 1/2 to 1 inch of water. Then pour your cheesecake batter into the springform pan.
Very carefully place the roasting pan with the cheesecake inside into the oven. Bake for 60-70 minutes until the there's about 2 in the centre of the cheesecake that still has a slight wobble.
Remove from the oven and using a very thin knife, trace around the outsides of the cake. Cool the cheesecake in the roasting pan until it's room temperature. Remove from the roasting pan, cover, and place in the fridge to chill for 6 hours or preferably overnight.
A few hours before serving (or more), make the ganache. The cheesecake should be fully cooled and have started the chilling process before topping.
Chop the semi-sweet chocolate into very small pieces and place in a large, heat-proof bowl.
In a small saucepan, heat the cream while gently stirring until it comes to a simmer for about 1 minute.
Pour the hot cream over the chocolate and let sit for 2 minutes, then whisk until smooth.
Remove the chilled cheesecake from the fridge, unclamp the outside of the springform pan.
Let the ganache cool for a few minutes, then slowly pour the chocolate ganache over top of the cake.
Chop the white chocolate into small pieces, place in a microwave-safe bowl, and microwave on medium power for 30-second intervals until melted.
Drizzle the white chocolate over the cheesecake.
Return to the fridge until ready to serve.
*Ingredients should be room temperature.**If you don't have a food processor, place the cookies in a ziploc bag and crush them with a rolling pin until they're fine crumbs.Store leftovers covered in the fridge for up to 4 days. Cheesecake can also be wrapped tightly and frozen for up to 2 months, then thaw in the fridge.