Bake the crust. Preheat the oven to 350℉. In a large mixing bowl, combine graham cracker crumbs, sugar, and melted butter. Press it into the bottom of a 9x13” baking dish sprayed with cooking spray. Bake for 10 minutes, then set aside.
Make the filling. In another mixing bowl, beat together cream cheese, sugar, and vanilla until smooth. Beat in eggs, one at a time. Add sour cream and 1 teaspoon of lemon juice and mix again until smooth. Pour cream cheese mixture over the prepared crust.
Add the guava. In a small bowl, mix together guava spread and 1 teaspoon of lemon juice until it reaches a smoother, thinner consistency. Drizzle the guava mixture over the top of the cheesecake mixture. Use a knife or toothpick to swirl it in.
Bake the cheesecake. Bake for 40-50 minutes (check at 40), until the edges are golden, the middle is just slightly jiggly. Remove from the oven.
Let it cool. On the counter top, let the cheesecake cool, then cover and refrigerate for at least 8 hours or overnight.
Serve. Cut it into bars, and serve. These are very rich, so I cut the 9x13" pan into 18 smaller rectangles.
Notes
To get the smoothest consistency, use room-temperature cream cheese.