A light and fluffy base makes this cake a delicious treat. Originally, it did not have the lemon zest, but the lemon adds a nice complement to the blueberries.
Preheat oven to 350 F. Grease 9-inch springform pan and line the bottom with parchment paper.
Make the filling: Add cream cheese, 1/4 c sugar and 1/2 tsp vanilla to a bowl and mix using medium-low speed until creamy. Add 1 egg white and lemon zest and mix on low until just combined. Set aside.
Make cake batter: In another bowl, stir 1.5 c all-purpose flour, 1/2 tsp baking powder, and 1/2 tsp baking soda. Set aside.
In the last bowl, using an electric mixer, cream together the 5.5 tbsp butter and 1/2 c sugar on medium-low speed. Add egg and egg yolk and 1 tsp vanilla extract. Slowly mix in the flour mixture, alternating with the sour cream. Transfer the batter into the prepared springform pan and smooth with a spatula. Sprinkle 1/3 cup blueberries. Spread the cream cheese filling on top. Place the remaining blueberries over cream cheese filling.
Make topping: Combine 1/3 c sugar, 1/2 c flour and 3 tbsp chilled cubed butter in a bowl. Pinch butter with fingers until mixture is crumbly.
Sprinkle the streusel on top of the blueberries and bake for 45 minutes until a cake tester inserted in the center comes out clean. Cool on a rack and run a thin knife around the cake and lose the ring of the springform pan. Store in the fridge.