Wrap the whole pan in aluminum foil so that no water can enter.
In a small pot melt the butter and continue to cook, stirring occasionally, until the butter has browned and smells nutty like hazelnuts.
Combine all ingredients for the crust and mix well. Press into the bottom of the springform pan.
Bake in preheated oven for 5 minutes. Cool completely.
Prepare the filling:
In a small bowl, whisk together the sour cream and heavy cream.
In the bowl of a stand mixer fitted with the paddle attachment, beat the cream cheese until silky, creamy and smooth. Beat in vanilla extract.
Add the sugar and beat until no granules are visible. It will begin to look shiny.
Add the eggs and egg yolk one at a time and beat after each addition.
Add the sour cream mixture and beat to combine.
Reduce mixer speed to low and slowly add the lemon juice. Increase mixer speed to incorporate well. The mixture will be looser so be careful not to turn it up too high.
Pour into prepared crust. Place pan in a large roasting dish and place in the preheated oven. Pour hot water into the pan approximately halfway up the sides of the pan.
Bake for for 1 hour and 40 minutes or until set but still wobbly. The top will puff a little and the whole cheesecake will move in one motion rather than like ripples of liquid.
Assembly:
Allow to cool completely before wrapping and refrigerating at least 4 hours or overnight.
Top with Fluffy White Frosting, which is just a simple Italian Meringue.
Torch using a kitchen torch or under the broiler. If using a broiler, work quickly and move frequently to avoid burning or over softening of the cheesecake.