Start by pouring the granulated sugar into an even layer in a large, heavy-bottomed saucepan. Heat the sugar over medium heat, stirring frequently with a heatproof spatula or whisk. The sugar will begin to clump as it heats but will gradually melt into a liquid. Continue stirring as it turns into a smooth amber-colored syrup. This process should take around 10 minutes. Once fully melted, stop stirring and let the sugar cook for an additional minute or two until it darkens slightly to a rich amber tone and begins to release a nutty aroma. Be cautious—this change happens quickly, and caramel can burn in seconds. As soon as it reaches the desired color, immediately remove the pan from the heat. Add the butter carefully—it will bubble up vigorously. Whisk continuously until the butter is completely melted and the mixture is fully combined. Slowly pour in the heavy cream, a little at a time at first, whisking constantly. As the mixture thins out, you can add the rest of the cream. Whisk until smooth and glossy. Measure out and set aside 1½ cups of the caramel sauce to be used later for the topping. To the remaining caramel in the saucepan, gradually whisk in sifted flour while the caramel is still warm, stirring constantly to prevent any lumps. Continue whisking until the flour is fully incorporated and the mixture is smooth. Set aside to cool slightly while you prepare the crust.

Preheat the oven to 325°F (163°C). Line the bottom of a 9-inch (23cm) springform pan with parchment paper and lightly grease the sides. In a small mixing bowl, combine graham cracker crumbs, sugar, and melted butter until the mixture resembles damp sand. Press the crust mixture firmly into the bottom and about 1 to 1½ inches up the sides of the prepared springform pan. Bake the crust for 10 minutes, then remove from the oven and let it cool completely. Wrap the outside of the springform pan tightly with a double layer of heavy-duty aluminum foil to prevent water from seeping in during baking. Reduce the oven temperature to 300°F (148°C). Once the crust has cooled, pour the thickened caramel-flour mixture into the crust and spread it evenly across the bottom.

In a large mixing bowl, beat the cream cheese, brown sugar, and flour together on low speed until completely smooth and creamy. Be sure to use low speed to minimize the amount of air being incorporated, which can lead to cracks in the finished cheesecake. Scrape down the sides of the bowl as needed to ensure everything mixes evenly. Add the sour cream and vanilla extract, continuing to mix on low speed until combined. Add the eggs one at a time, mixing slowly after each addition just until the yolk disappears. Scrape down the bowl as needed to maintain a uniform, silky texture. Once fully mixed, pour the cheesecake batter over the layer of caramel in the crust, smoothing the top with a spatula.

Place the foil-wrapped springform pan into a larger roasting pan. Carefully pour hot water into the outer pan until it reaches about halfway up the sides of the springform pan. Be sure the water does not go above the foil. Bake the cheesecake for 1 hour and 45 minutes. The center should appear set but slightly jiggly when gently shaken. After baking, turn off the oven and keep the door closed for 30 minutes, allowing the cheesecake to cool gently while continuing to cook slightly. After 30 minutes, crack the oven door open and let the cheesecake rest inside for an additional 30 minutes. This gradual cooling process helps prevent cracks from forming. Once cooled, remove the cheesecake from the water bath and take off the foil. Transfer the pan to the refrigerator and chill for 5 to 6 hours or until fully set and firm.

Once the cheesecake is completely cool and firm, carefully remove it from the springform pan and place it on a serving plate or cake stand. Just before serving, pour about ½ cup of the reserved caramel sauce over the top of the cheesecake and spread it evenly. Sprinkle toffee bits or crushed caramel candies over the sauce for added texture and a beautiful finish. Serve each slice with a drizzle of the remaining caramel sauce. For the best flavor and texture, store the cheesecake in the refrigerator in an airtight container or covered with plastic wrap. It will stay fresh for 4–5 days and can also be frozen in individual slices for longer storage.