Royal Layer Cake

Preheat the oven to 350 degrees Fahrenheit. Line the bottom of 2 or 4 (8-9 inch) round cake pans with parchment paper and grease with oil.
Beat 2 eggs with 1 cup of sugar in a standing mixer with a whisk attachment or use a hand mixer. Add 1 cup of sour cream, 1 teaspoon baking soda and ½ teaspoon vinegar. Mix to combine. Add 1 cup flour and mix to combine. Divide the batter in half and put the raisins into one half of the batter and the peanuts into the other half of the batter. Spread the batter evenly out into the prepared cake pans. Bake in the preheated oven for about 15 minutes.
Meanwhile, repeat with the remaining ingredients, dividing it in half again. This time, add the poppy seeds and cocoa powder to the batter. Spread the batter out evenly in 2 more round cake pans or wait until the first two cake layers have baked and use them to bake the remaining two cake layers on the same temperature.
Take the cakes out of the cake pans, cool on a rack.
Meanwhile, make the frosting. In a standing mixer fitted with a paddle attachment, or using a hand mixer, mix the butter and cream cheese until they are a smooth consistency. Add the condensed milk and vanilla. The amount of condensed milk depends on how sweet you like your frosting.
When the cake layers have cooled completely, even out the layers by cutting off the rounded part, if it needs it.
Assemble the cake by spreading the frosting between the layers. It doesn't matter which order you assemble the cake layers in. Cover the top and sides of the cake with frosting as well. You can simply use the reaming frosting or make additional buttercream frosting to make it more smooth and to use for piping a design around the edge of the cake. I used chopped peanuts and raisins and pressed them against the sides of the cake and used poppy seeds and buttercream frosting to decorate the top of the cake.
I didn't include the exact measurements for the buttercream frosting, because it's very basic - use a standing mixer or hand mixer and mix the softened butter and as much powdered sugar as you like, the more you use, the stiffer it will be. Add a little bit of milk if it becomes too stiff.
The texture of this cake is much more dense than a typical sponge cake, so don't expect it to be tender and fluffy. This is a different type of cake.It's best served at room temperature but should be stored in the refrigerator. The cake can be made ahead of time.