Preheat the oven to 190 degrees C. Grease a 23cm springform pan.
In a medium bowl, stir together the flour, 1/2 cup of sugar and baking powder. Mix in the butter by pinching between your fingers or using a pastry blender until the mixture resembles coarse crumbs. Stir in the egg and 1 teaspoon of vanilla. Pat lightly into the bottom of the prepared pan. Pour blueberries over the top.
In another medium bowl, whisk together the sour cream, 1/2 cup of sugar, egg yolks and 1 teaspoon of vanilla until smooth. Pour over the blueberries.
Bake for 60 to 70 minutes in the preheated oven until the top is lightly browned. Cool, then run a knife around the edge of the pan. Remove the outer ring of the pan, and cut into wedges to serve.