• The cake has to be made at least two days, preferably three days in advance.

Cake layers:

• Cream ingredients: Place the soft butter, eggs, smetana or sour cream, sugar, and vanilla sugar or extract in the bowl of the food processor. Mix until creamy.
• Mix dry ingredients: In another bowl, mix the flour and the baking powder. Add them to the rest of the ingredients and mix well.
• Refrigerate dough: Turn the mixture on the lightly floured working surface and knead shortly to obtain a smooth dough. Wrap the dough in cling foil and refrigerate for one hour.
• Preheat the oven to 200°C/400°F.
• Divide the dough into four equal parts. Cut four large pieces of baking paper. Flour the rolling pin.
• Roll: Flatten the first piece of dough on one piece of the baking paper to get a rough rectangle, and then roll it to a rectangle of about 23x30 cm/ 9x12 inches. It works better if you have a small rolling pin, which you can hold in one hand while holding the baking paper with the other hand. If you only have a regular-sized rolling pin, maybe someone can hold the baking paper for you, or you can fix it down with some tape.
• Trim edges: Try to push the edges of the dough with a butter knife or your fingers to make them a bit neater and to prevent them from being thinner than the rest of the rectangle so that they will not get excessively dry when baking. However, the edges do not have to be perfect; you can cut them straight and nicely after the cake has rested for the necessary two or three days.
• Bake first dough layer: Carefully place the dough on the baking tray and bake in the preheated oven for about 10 minutes or until the edges of the dough rectangle start to get brownish. Remove from the oven and let cool completely.
• Bake remaining layers: While the first cake layer is in the oven, roll the second one and so on until all four cake layers are baked.

Filling:

• Layer cake: When the cake layers are cool, layer them with jam. Stir the jam well before spreading it on the cake layers.
• Assemble the cake: Choose the nicest cake layer and set it aside to use it as the top layer. The first layer should be smeared with plum jam, the second with apricot jam, and the third one with plum jam again. Place the last cake layer on top and press gently.

Glaze:

• Mix the egg yolks, icing sugar, lemon juice, and vanilla extract in a small bowl.
• Prepare for glazing the cake: Place the layered cake on a large baking tray or wooden board. If using the wooden board, place that in a baking tray as well. This is necessary because some of the glaze will run down the sides of the cake.
• Start spreading the glaze on top. If the glaze is excessively runny, add more icing sugar until you obtain the desired consistency. If you need to add more icing sugar depends on the size of the egg yolks.
• Top the cake with colorful sprinkles. The cake can also be topped with roasted and chopped nuts of any kind or with chocolate sprinkles.
• Leave the cake to rest on the counter until the glaze is dry.

Store:

• Wrap the whole cake very well in clingfilm/plastic wrap, including the wooden board it sits on (or the baking tray/ casserole dish it sits on). I make a double layer and ensure there is no hole or anything.
• Leave the cake to rest for 2 or 3 days in a cool place. It doesn't have to be the fridge, but make sure is cool. I always keep it in the cellar.
• Cut the edges of the cake straight. Cut the cake into small squares.
• Keep in airtight cookie tins with baking paper between the layers of cake.