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.

CHEESECAKE

5. Reduce oven temperature to 300°F (148°C).
6. In a large bowl, beat the cream cheese, sugar and flour on low speed until well completely 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.
7. Add the sour cream, vanilla and lemon zest and mix on low speed until well combined.
8. 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.
9. Pour the cheesecake batter into the crust.
10. 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.
11. Bake for 1 hour 15 minutes. The center should be set, but still jiggly.
12. 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.
13. Crack the door of the oven for 30 minutes to allow the cheesecake to continue to cool slowly. This process helps prevent cracking.
14. Remove the cheesecake from the oven and let it sit at room temperature while you make the lemon curd.

LEMON CURD

15. To make the lemon curd, combine all the ingredients in a double boiler (or in a metal bowl over a pot of simmering water). Heat while whisking constantly until mixture thickens and reaches 170-180 degrees. You’ll notice it has already started to thicken nicely and it’ll continue to thicken quickly.
16. Add the lemon curd to the top of the cheesecake quickly, before it cools and thickens.
17. Place the cheesecake back in the fridge until completely cool and firm, 5-6 hours.

MERINGUE TOPPING

18. To make the meringue, combine the sugar, cream of tartar, vanilla extract and egg whites in a large mixer bowl. Place the bowl over a saucepan or pot of simmering water. You can also use a double boiler.
19. Whisk constantly until sugar is dissolved and egg whites are warm, at 160 degrees on a thermometer, about 4-6 minutes. Remove from heat.
20. Using the whisk attachment, beat the egg white mixture on low speed, gradually increasing to high, until stiff, glossy peaks form, 5 to 7 minutes.
21. Add the meringue to the top of cheesecake in a slight dome shape.
22. Use a kitchen torch to toast the outside of the meringue.
23. Refrigerate the cheesecake until ready to serve. Cheesecake is best if eaten within 3-4 days.