Remove the filing from Oreo cookies and place cookies in the food processor. Process until crumbs.
Add half pecans and 1 tbsp brown sugar. Process again.
Add melted butter and process until wet crumbs.
Prepare spring form pan. Smear the bottom and sides of the pan with butter. Cover the foil around the pan until half high of the sides.
Add Oreo crumbs at the bottom of the spring form pan. Make it smooth with a spoon. Bake the Oreo crust 10 minutes. Let it cool on the counter top or wire rack.
Lower the temperature of the oven to 300 F / 150 C.
Put cream cheese, brown sugar and flour in a large bowl. Combine with a hand mixer just until incorporated.
Add sour cream and vanilla flavoring. Mix until incorporated.
Add eggs one by one, mixing with hand mixer. Don't forget to scrape the sides of the bowl.
Put the spring form pan in a larger baking tray. Transfer the cream cheese filling on top of the Oreo base. Smooth the top with a spatula or spoon.
Fill the large baking tray with hot water until 1/3 of the cake pan. Bake 1 hour and 30 minutes until set, but slightly jiggly in center. Let it cool in the oven for 30 minutes, then open the door and let it cool further 30 minutes.
Transfer the cheesecake on the counter top or wire rack and let it cool completely for about 1-2 hours before placing in the fridge overnight. Run the knife around the cheesecake before placing it in the fridge.
Putt white sugar in a pan and cover it with water. Bring it to the boil. Keep cooking it about 20-30 minutes on low heat until browned. Don't stir!
Add butter to the caramel and whisk on a low heat until incorporated.
Add warm heavy cream and keep whisking on low heat until smooth.
Pour 1/2 of caramel on top of the cooled cheesecake. Move the pan to let the caramel spread around. Place the cheesecake in the fridge for 10 minutes until caramel is set. Transfer other half of caramel in the piping bag.
Add chopped dark chocolate in microwave-safe bowl. Cover with heavy cream.
Microwave chocolate sauce for 30-40 seconds. Stir until smooth and transfer to the piping bag.
Carefully remove the sides of the spring form pan.
Pipe chocolate sauce on top of the cheesecake, then drizzle caramel sauce in between.
Add remaining crushed pecans on top of the cheesecake.
Highly recommend drizzle more caramel and chocolate sauce on each slice!
Turtle cheesecake will last up to 5 days in the fridge.