Preheat oven to 350°F (180°C)
Prepare a 9-inch round cake pan with butter and flour, set aside
In a bowl, sift all-purpose flour, baking powder, baking soda, and salt
In a separate bowl, cream 1 cup softened butter and 1 cup granulated sugar until light and fluffy
Add 4 large eggs, one at a time, mixing well after each addition
Gradually add sifted dry ingredients to the butter mixture, alternating with 1.25 cups buttermilk, beginning and ending with dry ingredients
Stir in 2 cups fresh blueberries
In a separate bowl, beat 16 oz softened cream cheese and 1 cup granulated sugar until smooth
Add 4 large eggs, one at a time, mixing well after each addition
Gently fold in grated zest and juice of 2 lemons
Spoon half of the cake batter into the prepared pan, spread evenly
Drop spoonfuls of the cheesecake mixture over the cake layer
Spread the remaining cake batter over the top
Using a knife, marble the layers by gently swirling them together
Bake for 40-45 minutes, or until a toothpick inserted in the center comes out clean
Cool completely, then refrigerate for at least 2 hours before serving