Preparation
1. Preheat oven to 350 degrees F and thoroughly grease a 9×13-inch baking dish.
2. For the cake: In a medium-sized bowl, sift together flour, baking powder, baking soda, and salt until evenly combined In a large bowl, cream together butter and granulated sugar until light and airy. Mix in eggs and vanilla extract. Slowly add dry ingredients until just combined, then gently mix in sour cream. Set batter aside.
3. For the Filling: Add cream cheese to a medium-sized bowl and mix until smooth. Add sugar, vanilla, and egg and mix until well combined. Set aside.
4. For the Streusel: Add all dry ingredients to a small bowl and mix until evenly combined. Using a fork or your hands, cut in the cold butter until crumbles form.
5. To assemble: Pour half the cake batter in the prepared baking dish and spread into an even layer, then spoon cream cheese filling over batter. Pour remaining cake batter over top and use a knife to gently swirl filling and batter together. Sprinkle streusel evenly over the top.
6. Bake cake for 40-45 minutes or until center of cake doesn’t jiggle. Allow cake to fully cool before slicing.