Crust
14 tablespoons unsalted butter, melted and still warm
1/2 cup (3.5 oz) sugar
2 teaspoons vanilla extract
3/8 teaspoon salt
2 cups (9 oz) all-purpose flour
Filling
1 cup lemon curd (homemade or jarred)
1 1/2 lbs cream cheese, at room temperature
1/4 cup (1.75 oz) sugar
1 1/2 teaspoons vanilla extract
1/8 teaspoon Fiore di Sicilia (optional)
2 large eggs, at room temperature
To make the crust: Preheat oven to 350 F with a rack in the lower third of the oven. Line a 13x9 baking pan with parchment paper or foil, leaving an overhang so you can lift the bars out after they've baked. If using foil, spray it with nonstick cooking spray.
Combine the melted butter, sugar, vanilla and salt in a medium bowl. Stir in the flour until just incorporated - the mixture will be soft, that's fine. Transfer the mixture to the prepared baking pan and press into an even layer on the bottom of the pan. Bake for 20-25 minutes, or until the crust is golden brown. Let cool completely. Turn the oven down to 325 F.
In the bowl of a stand mixer fitted with the paddle attachment, beat the cream cheese on medium speed until smooth, about 30 seconds. Scrape down the sides of the bowl then add the sugar and vanilla, beating until smooth and creamy, about 1-2 minutes. Add the eggs, one at a time, beating just until incorporated and scraping down the sides of the bowl in between. Pour the remaining cheesecake batter over the cooled crust and spread evenly.
Dollop the lemon curd over the filling. Use a knife to gently swirl the lemon curd into the cheesecake mixture. Bake for 20-25 minutes, or until the edges are puffed and the center is just barely set.
Transfer the pan to a cooling rack and let come to room temperature. Cover and refrigerate for at least 4 hours, but preferably 24. Use the sling to lift the bars out of the pan and transfer to a cutting board. Cut into squares with a long sharp knife. The bars can be refrigerated in an airtight container for up to 4 days. Mine weren't in an airtight container and they cracked but were still delicious.