Preheat oven to 350°F. Line the bottom of the 6 inch spring form cake pan with parchment paper or foil.
In a large mixing bowl, add 4 eggs, room temperature , 120 grams granulated sugar , and ⅛ teaspoon salt . Beat on medium-high speed with electric mixer for about 12-15 minutes or until it triples in size, and when you lift the beaters, the mixture falls back into the bowl leaving thick ribbons that dissolve slowly.
In a second mixing bowl, whisk 70 grams flour , 35 grams cocoa powder , 20 grams cornstarch . Using a sifter, sift half of the flour mix into the egg mixture. Mix well with a silicone spatula. Sift in the remaining half of flour mix and mix again until the batter has smooth consistency.
Pour the cake batter into the prepared pan. Bake for 30 minutes without opening the oven. After 30 minutes, insert a tooth pick into the center of a cake. If it comes out clean, the cake is ready. If not, bake for another 3-5 minutes or until the tooth pick comes out clean.
Let the cake cool down for 5 minutes. Use a sharp knife to go around the edges of the cake to loosen it. Remove the cake from the pan and place it on a wire rack to cool down for about 30-40 minutes. While it is still slightly warm, wrap it in a plastic wrap and place it in the fridge for at least one hour.
Carefully, slice it into 3 layers. Place the first layer on a cake stand. Add about one tablespoon of syrup on top. After that, spread a generous amount of frosting. Place the second layer and repeat the process with the rest of the layers. Now, cover the whole cake with the thin layer of frosting, top and sides. Place it in the fridge for at least one hour and enjoy.