Make the caramel sauce:

1. Pour the sugar into an even layer in a large saucepan. Heat over medium heat, stirring the sugar most of the time, until melted. The sugar will clump up at first, but will eventually completely melt. This should take about 10 minutes.
2. Once the sugar has melted, stop stirring and allow to cook until the sugar has turned to a little darker amber color, if needed. You may notice a nutty aroma. The change in color will happen quickly, so don’t let it go too long or get too dark, or it’ll burn. Remove the caramel from the heat.
3. Add the butter and whisk vigorously until combined. The mixture will bubble up quite a bit, but keep whisking until all the butter has melted and is combined.
4. Slowly pour the heavy cream into the caramel and whisk until incorporated. It helps to add just a bit at a time until the caramel starts to thin out, then you can add the rest. Whisk until well incorporated and smooth.
5. Set about 1 1/2 cups of caramel sauce aside for topping. While stirring with a whisk, slowly add sifted flour to the remaining caramel sauce to prevent lumps. Whisk until fully incorporated.

Make the crust:

1. Preheat oven to 325°F (163°C). Line a 9-inch (23cm) springform pan with parchment paper in the bottom and grease the sides.
2. Combine the crust ingredients in a small bowl. Press the mixture into the bottom and up the sides of the springform pan.
3. Bake the crust for 10 minutes, then set aside to cool.
4. Cover the outsides of the pan with aluminum foil so that water from the water bath cannot get in (see how I prepare my pan for a water bath). Set prepared pan aside.
5. Reduce oven temperature to 300°F (148°C).
6. Pour the caramel sauce with the flour into the bottom of the crust and spread into an even layer.

Make the cheesecake filling:

1. Beat the cream cheese, brown sugar and flour in a large mixer bowl on low speed until well combined and smooth. Be sure to use low speed to reduce the amount of air added to the batter, which can cause cracks. Scrape down the sides of the bowl.
2. Add the sour cream and vanilla extract and mix on low speed until well combined.
3. Add the eggs one at a time, mixing slowly to combine after each addition. Scrape down the sides of the bowl as needed to make sure everything is well combined.
4. Pour the cheesecake batter into the crust, over the caramel.
5. Place the springform pan inside another larger pan. Fill the outside pan with enough warm water to go about halfway up the sides of the springform pan. The water should not go above the top edge of the aluminum foil on the springform pan.
6. Bake for 1 hour 45 minutes. The center should be set, but still jiggly.
7. Turn off the oven and leave the door closed for 30 minutes. The cheesecake will continue to cook, but slowly begin to cool as well.
8. Crack the door of the oven for 30 minutes to allow the cheesecake to continue to cool slowly. This process helps prevent cracking.
9. Remove the cheesecake from the oven and remove the water bath and wrapping.
10. Refrigerate cheesecake until completely cool and firm, 5-6 hours.

Finish the cheesecake:

1. When the cheesecake is cool and firm, remove it from the springform pan and place on a serving dish.
2. Prior to serving, pour 1/2 a cup of the remaining caramel sauce over the cheesecake and sprinkle with some toffee bits. Serve cheesecake slices with the remaining caramel sauce, for drizzling.
3. Store cheesecake in the fridge in an air-tight container or covered with wrap. Cheesecake is best if eaten within 4-5 days.