Preheat the oven to 350°F. Line a 9"x13" baking pan with a sheet of parchment, leaving extra draped over the long edges for "handles" to remove the bars after baking. Spray the parchment paper and pan with cooking spray.
To a food processor, add the graham crackers and process until the crumbs are fine. Add the melted butter and the sugar and pulse to combine. Scrape the sides of the processor and pulse a few more times to fully incorporate the ingredients.
Without a food processor, place the graham crackers in a zip bag and crush with a rolling pin or mallet until finely crushed. Combine the crushed crackers, butter, and sugar until well mixed.
Pour out the cracker mixture into the prepared pan and pack the crumbs tight into a smooth layer. Use your hands or the bottom of a flat glass or measuring cup.
Bake for 10 minutes at 350°F and then set aside.
Prepare the Cheesecake Filling
Brush out the crumbs from the food processor after making the crust. Add the cream cheese, Greek yogurt, vanilla, lemon zest, and sweetened condensed milk to the bowl of the food processor.
Process until the mixture is smooth. Scrape down the sides of the bowl and pulse a few more times to make sure everything is fully incorporated.
Without a processor, beat the cream cheese in a large bowl with an electric mixer until smooth. Add the Greek yogurt, vanilla, lemon zest, and the sweetened condensed milk. Mix until fully incorporated, scraping down the sides of the bowl once.
Bake the Bars
Pour the cheesecake filling over the baked cookie crust and spread with a spatula to coat the crust evenly.
Using a spoon, make lines of the lemon curd along the short side of the pan. Use a knife to swirl and marble the curd into the cheesecake filling by dragging the knife through the lines (along the long sides of the pan) and then in the opposite direction (diagonally or along the short sides of the pan). Swirl until you see the marbled effect you desire, but take care not to score the graham crust with your knife.
Bake the bars for 22-25 minutes, or until the center of the bars doesn't jiggle and the edges are very lightly browned. The curd will be runny but will set while it cools.
Cool the bars for 30 minutes on the countertop and then cover them with a clean kitchen towel or plastic wrap. Transfer to the refrigerator for at least 3½ hours more. Overnight chilling is recommended. Take care when removing the plastic film that any water condensation doesn't drip onto the surface of the cheesecake bars.
Score around the edges of the pan with a knife. Remove the bars from the pan using the parchment paper handles and place them on a cutting board. Slice, using a sharp knife, into 24 pieces. For clean edges, rinse the knife off in warm water and dry it after every slice.
Nutrition facts are sometimes provided below and are calculated using an online calculator. With specific brands of ingredients and additions, omissions, or substitutions the nutrition facts may change. We encourage you to use your own nutrition facts calculator to obtain the most accurate nutrition facts for your meal.