Prepare the dough. Heat water and dissolve yeast and sugar in it, melt 25 g of butter. Beat an egg into the cooled mixture. Add a pinch of salt, sour cream and sifted flour. Mix. Roll the dough into a ball and leave it under a towel for 90 minutes in a warm place.
Prepare the filling. Grind 150 grams of walnuts and add powdered sugar and cinnamon. Mix.
Prepare the baklava for baking. Roll the finished dough into a sausage and divide it into 12 parts. Grease the baking pan with vegetable oil. Roll one of the dough parts into a thin layer and stretch it over the baking pan. Melt 1 tbsp. butter. Grease the bottom layer of dough with it. Then roll out the second layer. Grease it with butter and sprinkle 1/10 of the filling. Roll out the dough and lay it out, oiling and sprinkling with filling. Seal the edges of the bottom layer on top of the baklava. Beat the egg and grease the top layer with it. Make diamond-shaped cuts. Put half a walnut in the middle of each diamond. Bake the baklava in the oven for 15 minutes at 180 ℃.
Make the syrup. Mix hot water with honey. Remove the baklava from the oven and pour the syrup over it so that it is completely soaked. Bake the baklava for another 10 minutes. Cool the baklava completely. Then cut it into diamonds and let it sit for 20 minutes.