Pre-heat oven to 325 F (160 C).
Prepare a 9-inch springform pan by unrolling a piece of heavy-duty, wide, aluminum foil that is long and wide enough to come up the sides of the pan without any gaps. Set the pan in the center of the foil, and fold the foil up around the pan, creating a water-tight seal around the base of the springform.
Add the butterscotch crumbs to the pan and using your hands, firmly press crumbs into an even layer, right to the sides of the pan. Place into a large roasting pan, and set aside. Tip: Try using your fist – not fingers – to press crumbs to get closer to the sides of the pan for a crust that won’t crumble at the edges.
In the bowl of a stand mixer or in a large bowl with electric hand beaters, beat cream cheese until soft and smooth.
Add sugar and continue beating until well blended and smooth.
Add eggs, vanilla and sour cream, and blend until fully incorporated.
Add flour and pecans and blend until fully incorporated.
Set prepared pan into a larger roasting pan. Pour filling mixture into the prepared pan, then pour hot or just boiled water around the springform, into the large roasting pan, to come up the side of the springform about 2-inches.
Bake for approximately 50 to 60 minutes, or until center feels almost set when lightly pressed with the fingers.
Lift springform out of the water bath and set on a rack to cool. While still warm, run a dinner knife around the edges of the pan to release the cake from the sides. Do not try to remove from the base until completely cooled.
Serve with caramel sauce (optional).