Cream Cheese Filling
Preheat oven to 350º F.
Cream together butter and sugar until pale yellow and creamy. Add egg and vanilla and beat in.
Sift together flour, baking powder and salt. Add alternately with milk until incorporated. Scrape batter into cake pan and spread evenly.
Beat cream cheese until very smooth. Gradually add sugar, scraping the sides of the mixing bowl well. Add vanilla and blend. Add egg and mix well.
Spoon cream cheese filling over cake batter. Top with blueberries.
In small bowl blend sugar, flour and cinnamon. Cut in butter with your fingers until crumbly and no large bits of butter are visible.
Sprinkle streusel on top of berries and bake for 50-60 minutes.
Cool completely before slicing.