Sift the flour. Butter cut into pieces. To combine the flour, butter, baking powder and granulated sugar (1/2 Cup). Grind with fingers to a state of crumbs. Add chopped in a blender, nuts. Mix well. Curd connect with egg, sugar and sour cream. Apples to grate on a coarse grater and add to the cheese and egg mixture. mix well. Refractory form to lay baking paper, put on the bottom 2/3 of the shortbread crumbs, then filling, flatten and sprinkle with remaining crumbs. Bake in a preheated 200 g oven - 40-50 minutes. In my experience sour cream in the filling can be replaced with yogurt, it turns out not worse.