Preparation Steps

• Preheat oven to 350°F (175°C). Grease and flour a 9x13 inch baking pan.
• In a large bowl, whisk together flour, baking powder, baking soda, and salt.
• In a separate bowl, combine sugar, oil, vanilla extract, sour cream, and eggs. Beat until smooth.
• Gradually add the wet ingredients to the dry ingredients, mixing until just combined. Gently fold in the blueberries.
• In a medium bowl, beat together cream cheese, sugar, egg yolk, and vanilla extract until smooth and creamy.
• In a small bowl, combine flour and brown sugar for the topping. Cut in the cold butter until the mixture resembles coarse crumbs.
• Pour half of the cake batter into the prepared pan. Spread the cream cheese filling evenly over the batter. Pour the remaining cake batter over the cream cheese filling. Sprinkle the crumble topping evenly over the cake.
• Bake for 40-45 minutes, or until a toothpick inserted into the center comes out clean.
• Let cool completely before slicing and serving.