Step 1

Preheat oven to 325 degrees F.

Step 2

Lightly grease a 9x13 baking dish with nonstick cooking spray. Line the greased baking dish with heavy-duty aluminum foil going the length of the pan, allowing the long ends to overhang by at least a 2-inches (to easily lift cheesecake out later). Line the pan with foil going the other direction (width of the pan to create a +). Lightly grease foil with nonstick cooking spray. Set aside. (Yes, you grease the pan and the foil – it helps the foil release more easily.)

Step 3

Melt butter in a large microwave safe bowl. Add finely ground Graham crackers and sugar and stir until well combined. Transfer crumbs to prepared pan and firmly press the crumbs down on the bottom of the pan using the back of a measuring cup until you have an even layer.

Step 4

Bake at 325 degrees F for 14 minutes. Remove and set aside to cool COMPLETELY.

Step 5

Add cream cheese to the bowl of an electric mixer fitted with the paddle attachment and beat on medium speed until light and fluffy, about 4 minutes (no less!). Add sugar and beat 5 additional minutes on medium speed.

Step 6

Add the sour cream, lemon juice, lemon zest and vanilla and mix until blended. With the mixer running on low, add the eggs one at a time followed by the egg yolk, beating as little as possible, just until combined after each addition (overbeating once you add the eggs can cause cracks and the cheesecake to deflate).

Step 7

Pour cheesecake on top of the COOLED crust and evenly spread to the edges.

Step 8

Bake for 60-70 minutes at 325 degrees F, until the filling is set around the edges but still a little jiggly, but not runny, in the center (DON'T peak earlier because opening the door can cause cracks). An instant-read thermometer inserted into the filling about 1-inch from the edge should read between 175°-185°F. (The cheesecake will continue to cook as it cools.)

Step 9

Once the cheesecake bars are done, crack the oven door and let them cool in the oven for 15 minutes, then remove the pan from the oven to a cooling rack. Let the cheesecake cool for 1 hour before adding the lemon curd topping.

Step 10

Whisk the lemon juice, sugar, cornstarch, eggs and egg yolks in a medium bowl until the cornstarch dissolves and most of the sugar has dissolved.

Step 11

Pour the lemon mixture into a small, saucepan and cook over medium-low heat, stirring CONSTANTLY, until thickened to the consistency of thick pudding, 4-8 minutes, and the curd registers about 175°F on an instant-read thermometer.

Step 12

Immediately remove the saucepan from heat and stir in butter until melted, followed by vanilla and salt.

Step 13

Strain the lemon curd through a fine-mesh sieve into a small bowl. Set aside to cool to warm temperature before spreading over the cheesecake.

Step 14

Pour all of the room temperature lemon curd onto the cheesecake and spread into an even layer.

Step 15

Let the cheesecake cool to room temperature, another 1-2 hours, then cover and refrigerate for at least 6 hours before serving, but preferably overnight.

Step 16

Optional for stabilized whipped cream: Add unflavored gelatin to a microwave safe bowl then pour the cold water over top; let stand for 5 minutes then microwave for 10 seconds. Stir the mixture, then set aside to cool.

Step 17

Add heavy cream, powdered sugar, and vanilla extract to a large mixing bowl. Whip using an electric hand mixer just until soft peaks form.

Step 18

Turn the mixer to low and slowly pour in the gelatin mixture. Mix until well combined then increase the speed to medium and continue mixing until stiff peaks form.

Step 19

Transfer whipped cream to a piping bag fitted with a large tip. You can pipe the stabilized whipped cream onto the room temperature cheesecake with lemon curd topping before you pop it into the fridge or any time after that.  The beauty of stabilized whipped cream is it will hold its shape indefinitely.  If using regular whipped cream, top just before serving.

Step 20

When ready to serve, use the foil overhangs to lift the cheesecake out of the pan onto a cutting board.

Step 21

This next step is CRUCIAL for clean cuts. To slice, fill a tall glass with hot water. Dip a sharp knife in the hot water, wipe with a damp cloth, then make a clean slice; repeat for reach cut.