Add the sugar and water to a light-colored, heavy-bottomed saucepan. Heat on medium, stirring occasionally until the sugar dissolves completely. Stop stirring. 

Use a wet pastry brush to clean the sides of the saucepan if there are any sugar crystals clinging to them. 

Continue to cook the sugar until it becomes a deep amber color. Turn off the heat immediately. 

Add in the butter and heavy cream and stir until fully incorporated. Be careful, as the mixture will bubble and sputter. Stir in the vanilla. 

Pour the caramel sauce into a container and set aside to cool completely. 

Preheat oven to 350°F (180°C). Spray bottom of a 9-inch springform pan with baking spray with flour. Line the bottom of the pan with parchment paper.

Pulse oats in the bowl of a food processor until finely ground. Add almond flour, ¼ cup (50 grams) sugar, ¼ teaspoon salt, and cinnamon; pulse a few times just until combined. Add melted butter, and pulse until well combined and mixture holds together when pressed. Using a small measuring cup or bottom of a glass, press crumb mixture into the bottom of the prepared pan.

Bake until set and fragrant, about 15 minutes. Let cool on a wire rack for 30 minutes. Wrap bottom and sides of pan in a double layer of heavy-duty foil; place in a large oven bag, tucking ends so the bag is flush with the top edge of the pan. Reduce the oven temperature to 325°F (170°C).

Beat cream cheese in the bowl of a stand mixer fitted with the paddle attachment at medium speed until smooth and creamy, 1 to 2 minutes, stopping to scrape sides of bowl. Add all-purpose flour, vanilla bean paste, remaining 1½ cups (300 grams) sugar, and remaining ¼ teaspoon salt; beat at low speed just until combined. Increase mixer speed to medium, and beat until well combined, about 1 minute, stopping to scrape sides of bowl. With the mixer on medium-low speed, add eggs, one at a time, beating just until combined after each addition. Add sour cream and cream; beat until well combined, 30 seconds to 1 minute, stopping to scrape sides of bowl.

Separate 1 cup of the caramel and stir in the ¼ cup flour and the pecans. 

Spray sides of the prepared pan with baking spray with flour. Pour cream cheese mixture onto prepared crust.  Swirl in the 1 cup of caramel. Lightly tap sides of pan to spread batter into an even layer and release any air bubbles. Using a wooden pick, pop and fill any air bubbles that rise to the surface. Carefully place the springform pan in a large roasting pan. 

Position the oven rack so the top of the springform pan is 5 to 5½ inches from the top heating element; place a roasting pan in the oven, and add hot water to come 1 inch up sides of the springform pan.

Bake until edges are set, top looks dry, center is almost set but still jiggly, and an instant-read thermometer inserted in center registers 150°F (66°C) to 155°F (68°C), 1 hour and 10 minutes to 1 hour and 25 minutes, loosely covering with foil to prevent excess browning, if necessary. Turn off the heat and leave the cheesecake in the oven for at least an hour as the oven cools. Let cool in the pan on a wire rack for 1½ to 2 hours. 

Refrigerate cheesecake in the pan on a wire rack overnight, loosely covering with foil only when completely cool to prevent condensation from forming on top of cheesecake. 

Make the ganache and topping while the cheesecake cools. Heat the heavy cream until steaming, but not yet boiling. Add the chocolate and allow it to sit for 5 minutes. Stir to combine completely. 

Whip the cream cheese and granulated sugar for the topping until smooth and creamy. Add in the heavy cream and mix until combined. Whip until the mixture becomes light and fluffy.

Carefully remove chilled cheesecake from the pan, and transfer to a serving plate. Top with the chocolate ganache. 

Fill the bag with the topping and pipe on top of the cheesecake. Drizzle with some of the remaining caramel, then the chocolate turtles. 

Use a warm, dry knife to slice when ready to serve.