Grease a baking pan size 20x30 cm with fat. Separate egg whites from yolks. Beat the egg whites with 1/3 the sugar of thick snow. Beat the egg yolks with the remaining sugar until white set and double volume. Then add the melted and slightly cooled butter and a spoon of water and continue mixing. Sift flour and add him. Finally put the milk and vanilla. Start adding parts of egg whites, stirring with a spoon or spatula until fully absorb the mixture (gets quite rare, but it should be). Pour into the pan and put in the oven at 170C degrees for about 40 minutes. Cake is ready when the surface is formed cake base and red as any baked. But when they cut you will see that have formed two the base - bottom milk and thick cream on top and fluffy cake board. Before serving dessert should cool to harden well. Finally, sprinkle with powdered sugar and decorate as per your taste.