Sponge cake with chocolate buttercream {Dobos torta}

''Dobos torte or Dobosh, a Hungarian sponge cake layered with chocolate buttercream and topped with caramel was invented by the famous Hungarian confectioner Jozsef C. Dobos in 1884, who aimed to create a cake that would last longer than other pastries in an age when cooling techniques were limited.'' Source-Wikipedia

Not really hard to make but it takes some time since you have to bake 10 layers of sponge. This cake tests delicious and the more it stands, it tastes better. For the best results, cake should be made at least one day in advance. This is my version of cake, I adapted it to my taste, it's very similar to original and it tastes great :) I promise :)
Recipe that I adapted to my taste is here.
Ingredients: For 20 cm diameter cake // 10 big pieces 

For the sponge:

• 9 eggs
• 9 spoons of sugar
• 9 spoons of flour
• 3 spoons of lemon juice

For the buttercream:

• 6 eggs
• 200 gr dark chocolate at least 70% cacao
• 200 gr sugar
• 180 gr butter (unsalted real butter)
• 2 teaspoons vanilla extract
• 1 teaspoon lemon zest

For decoration:

• 150 gr sugar
• 20 gr butter
• 2 spoons of lemon juice

*****I added strawberries and whipped cream 

to spice it up little bit and it was perfect!*****

Preparation:

1. Preheat your oven to 200 C degrees.
2. Prepare baking paper and use some 20 cm diameter plate as mold for circles that you will draw on the baking paper. Prepare 10 baking sheets with a drawn circles. 
3. Mix 3 eggs whites will fluffy then add egg yolks, 1 by 1, with constant mixing add sugar and 1 spoon of lemon juice and at the end add 3 spoons of flour. Mix shortly and your 1st cake mixture is ready. Do same thing two times more with another 3 eggs after you bake your first 3 cake bottoms. You can start mixing when 3rd bottom is baking.
4. Divide the cake mixture on 3 baking sheets. Spread it into circles that you draw on the baking paper. Put it in the oven, 1 by 1, and bake 2-3 minutes. Stay close so you can watch over cake bottom, since it's a tiny layer, it will be baked very fast, maybe in 2 minutes only. When it gets nice golden color, take it out and let it cool. Do this to all 9 cake bottoms.
5. After minute or two, remove baking sheet slowly from your sponge and place all sponges on the top of each other. Cover it with kitchen towel and let it cool.
6. To make buttercream, start with mixing eggs till fluffy, add sugar and vanilla extract. Mix it well then cook it in a steaming pot (place one large pot filled half with water on the stove. Let it boil. Then use smaller pot and pour in your cream mixture and place it on large pot). Stir constantly for 15-20 minutes. Cream is cooked when you see the bottom after you pull spoon through cream.
7. Remove from the steaming pot and add chocolate. Stir all together. Let it cool.
8. Stir room temperature butter into cold cream, stir it well. Add lemon zest and stir more.
9. Your cream is ready and now you can layer the cake.
10. Place one sponge on cake stand and 2-3 spoons on cream on it. Spread cream and lay down another sponge and repeat the process for all 8 sponges. Finish the last one with cream. You will have extra cream left, use that to cream up side of your cake. 
11. 10th sponge you will use for decoration. Keep the cake in the fridge till next day when you will finish the decoration and serve the cake.
12. Melt sugar on the stove till brown (caramelize it), then add butter and lemon juice. Stir well.
13. Cut your sponge on smaller pieces I made 12, but I used 10 only. Place them on the baking paper.
14. Pour caramel over cutted sponge and cover them all. Don't touch the caramel with fingers, it's very very hot it can burn your fingers :).
15. Let it cool. 
16. Cut caramelized triangles and lay them on the top of the cake. Decorate with strawberries and whip cream like I did, if you like and enjoy :)