Break cookies into crumbs using a rolling pin and mix with melted butter, cinnamon, and brown sugar.
Wrap springform pan with foil 3-4 times.
Press cookie mixture into bottom and up sides of pan.
Bake at 180°C (350°F) for 10 minutes.
Mix cream cheese with sugar, cinnamon, vanilla, and sour cream.
Add corn starch and mix.
Add eggs one at a time, mixing gently.
Pour filling over crust.
Peel and thinly slice apple, arrange on top, and sprinkle with cinnamon and sugar.
Combine oatmeal, flour, brown sugar, cinnamon, and melted butter until it resembles wet sand.
Sprinkle over apples.
Place pan in larger baking dish and pour boiling water halfway up sides.
Bake at 180°C (350°F) for 60 minutes.
Cover with foil if browning too quickly.
Cool in oven with door ajar for 1 hour, then refrigerate 6 hours or overnight.
Drizzle with caramel before serving.