Add the baking powder to the flour. Add the flour gradually in 3 times, mix well after each time
Using hands, mix the dough till well blended and smooth and form a ball. Put the dough ball on a working surface, and with the hands, form a small log (like the shape of a soda can). Divide the dough in 2. Wrap each piece of dough in plastic wrap and put in the freezer for 30 minutes
To make the yogurt cream filling
Beat the egg white with a hand mixer until soft peaks form (around 3 minutes)
Add the sugar, and mix well by hand mixer
Gradually add the plain yogurt in 3 times, and mix after each time by hand mixer
Add the flour, mix well by hand mixer.
To assemble the cake and bake
Preheat oven to 365F / 280C
Grease a cake baking pan, add around 2 tablespoon of flour and shake the pan so the flour evenly coats the bottom and sides of the pan.
Press 1 of the dough ball into the pan in your fingers, to flatten and cover the bottom of the cake pan. This is the base of the cake.
Pour the yogurt creamy mixture on top and with a spatula spread the top to even up
With the remaining dough ball, grate it over the yogurt filling to evenly cover the whole surface, like a cake crumble. If you prefer, you can grate the dough first over a plate, then sprinkle all over the cake.
Put the cake in the middle level of the oven and bake for 35 minutes.
When time is up, remove from the oven, let cool. Before serving, sprinkle powdered sugar on top.