In a large mixing bowl, with your electric mixer on medium speed, beat the cream cheese until smooth and creamy.
Add the eggs, one at a time, mixing well after each addition.
Add the vanilla extract, lemon zest, lemon juice, and sugar. Beat until the mixture is smooth.
Pour the cheesecake filling over the cooled graham cracker crust in the baking dish. Use a spatula to smooth the top.
Spoon dollops of the cooled blueberry sauce onto the surface of the cheesecake filling. Use a toothpick or knife to create a swirling pattern, gently dragging the blueberry sauce back and forth through the cheesecake batter.
Press the 1/4 cup of blueberries you put back in the freezer in the first step of this recipe into the top of the cheesecake. Space them out when doing this step.
Place the baking dish in the preheated oven and bake the cheesecake bars for 40-45 minutes, or until the edges are browning and set and the center is slightly jiggly.
Remove the cheesecake bars from the oven and let them cool completely at room temperature. Once cooled, cover the baking dish with plastic wrap and chill the cheesecake bars in the refrigerator for at least 4 hours, or overnight, until firm.