When making cakes, the temperature of ingredients is always the most important. The best results are when the butter and ingredients are always at room temperature. The temperature in the room where you make cake should be between 19 to 23 degrees Celsius. I always try to set it to 20-22 degrees. For this cake, put the butter at room temperature into the dry ingredients, mix evenly, and then add the liquid ingredients at a time and mix. After adding the sour cream, mix for about 2 minutes to make the batter smooth. There are a lot of ingredients. It was a little difficult to mix using a hand mixer. If you have a stand mixer, you'd better to use it. The egg white is also at room temperature. This white was about 22 degrees. Whip the meringue at medium speed. After about 40 seconds of whipping, and when it becomes like beer foam, add 1/3 of the sugar and continue whipping. After that, build meringue by adding 1/3 of the sugar every 30 seconds. The meringue should be smooth and firm. Add only 1/3 of the meringue and mix. Fold with a spatula. I do not mix the meringue completely. If the meringue is 80% mixed, add another 1/3 and mix. Also, if the meringue is 80% mixed, add the last meringue and mix. You will get a light-textured batter. Three pans are lined with parchment paper on the bottom only. Divide into three pans (at least two pans). It is not recommended to bake all in one pan. I'm going to make a flour milk paste for the Ermine(flour) buttercream. Flour must be sifted. That way, it doesn't clump. Mix the powdered ingredients evenly. First, add a little milk and moisten it evenly to avoid lumps. Add the rest of the milk and mix until homogeneous. Make sure there is no flour lump left on the bottom or in every corner. Bring it to boil slowly over low heat. It takes a long time, but you should do it. Suddenly, the mixture starts to thicken. Stir the bottom of the pot constantly to prevent it from scorching. It gets thicker and thicker. Keep stirring. When the big bubbles rise like this, boil while stirring for another minute. Transfer it to a bowl, put the cling wrap on the paste surface, and let it cool completely. At this time, the temperature of the butter was 22 degrees. Cream enough for 4 minutes at medium speed of the hand mixer. Add the flour milk mixture (room temp.)to one scoop and mix thoroughly. The moisture of the paste will change each time when it is made. So you need to watch carefully to make sure the butter isn't curdled. Control whether you're adding the last scoop in or not. I have tested with the recipe several times and set it to a quantity the butter will not curdle even if the paste is added, but please keep it in mind. After tasting, I added a little more vanilla extract and Kirsch. If you don't have Kirsch, you can add a little lemon juice or rum. I trimmed the top, bottom, and sides of the sheets. I'll write the sugar syrup recipe in the description box. Did crumb coat and put it in the refrigerator to chill. I added sky blue food coloring. I gave a wave pattern with a comb scraper. Ah... again!.... The cake sheet looks dense, but it isn't. So~ soft~!
