Make Dough: In a medium bowl, mix 1 ¾ cups flour, salt, and baking powder. Add butter cubes and blend with a pastry blender until a coarse meal forms. 2. Beat egg with sour cream, then add to the flour mixture. With your fingers, blend together until incorporated. Transfer to a floured surface, knead until a ball forms. Cover with wrap and chill 30 minutes. 3. Prepare Filing: Heat the oil over a nonstick, large skillet set over medium heat. Cook the hash browns about 10 minutes, stirring every 30 seconds. Mix in the salt, pepper, cayenne pepper. Add the cooked bacon crumbs and cook another minute. Remove from heat and cool to room temperature. 4. Add in 2 whisked eggs, the 2 cheeses and basil. Blend well. 5. Preheat oven to 400 degrees F. (375 degrees for dark pan). Grease and line with parchment paper 2 large baking sheets, grease paper. Set aside. 6. Roll out half of the dough into a large rectangle, 1/8 inch thick. Cut out 2 inch squares, or 3 inch circles, with a cookie cutter. 7. Place a heaping teaspoon of the filing in the center of each square, or circle. Fold dough diagonally across in half, forming a half moon or triangle. Pinch the edges together to seal. Press on the edges with fork tines. 8. Place the sealed piryshky onto the prepared baking sheets 2 inches apart. Repeat process until all dough and filing used. 9. Whisk 1 egg with 1 tablespoon water or milk. Brush the egg wash over each. 10. Bake about 15-16 minutes until golden and the crust is cooked through. Let rest on baking sheet 2 minutes. 11. To Serve: Plate and serve warm piryshky with sour cream or yogurt mixed with some basil.