Start making the cake 2 days before serving. In the evening make the dough and put in the fridge to rest. The next day, bake and assemble the cake. Chill overnight or at least 8 hrs before serving!
Fill medium saucepan one quarter full with water. Bring water to a simmer over medium heat.
Combine all the ingredients (except flour) in a large mixing bowl and place over saucepan. Whisk constantly until sugar is dissolved and mixture is warm to the touch, 4–5 minutes. Test by rubbing between your fingers.
Remove from heat and stir in 2 cups (280 gr) of the flour with a wooden spoon. The dough is going to be soft. Stir in the last ½ to ¾ cups of flour ¼ cup at a time. The dough should not be too thick, but rather on a softer side. The softer the dough, the lighter and spongier will be the cake layers.
Cover the bowl with plastic wrap and refrigerate for 8-12 hours. Аfter 8 hours the dough will thicken.
Shape and bake the cake layers:
Heat the oven to 200°C/400°F.
Lightly flour your counter and divide dough into 8 even pieces; roll each piece into a ball.
Get 2 large baking sheets and 3 or 4 parchment paper sheets large enough to have two 9-inch (23-cm) circles on it (or 6 sheets large enough for 1 circle); draw circles on them (you can use bottom of a 9-inch cake pan or a similar size plate).
Sprinkle parchment with flour, put a piece of dough on it and stretch with hands or roll between two sheets of parchment paper to a round slightly bigger than 10-inch, trying to maintain a uniform thickness. The dough is soft and very obedient, but a little bit sticky, so lightly dust your hands and dough with flour to keep it from sticking.
Brush off the excess flour and transfer the parchment with dough disks to the baking sheet. Bake for 4-5 minutes (first tray a bit longer, up to 7 min) or until cakes light golden brown around the edges. Slide the cakes onto a cooling rack. Reuse the parchment for other layers.
While the first tray is baking, roll out next disks so they are ready to go into the oven as soon as the first tray comes out.
Trim cake layers to an even 9-inch circle while they're still warm. Save the trimmings.
Put all of the cake trimmings on sheet of parchment and bake until light golden, 3–5 minutes. Let cool completely. Place trimmings into a freezer bag and bash them into crumbs with a rolling pin. Save until you’re ready to decorate the cake.
For the Filling and Frosting:
Beat heavy cream with an electric mixer on medium–high speed until fluffy and soft peaks form.
Gradually add sugar and beat until stiff peaks form, 1-2 min on high speed.
Add the sour cream into the whipped cream 1 Tbsp at a time and mix on low speed. Do not over beat or the filling will become too thin.
Add vanilla extract or cognac and blend in.
Assemble and finish the cake:
Spread about ⅓ cup frosting on each cake layer (visually divide the cream filling into 9 parts: 7 parts for the cake layers and 2 — for frosting the top and sides). Leave 1-inch unfrosted margin around the edge of the layer. Press gently the cake layers down as you go to keep the layers from sliding (be generous with filling, because the cake needs to absorb the cream to become soft and moist). Frost the top and sides with the remaining frosting.
Press reserved crumbs to the sides of the cake.
You may sprinkle the top with the crumbs or decorate it with berries or your desired toppings.
Put the cake in the refrigerator for 8-12 hours or overnight.
Recipe by Мои кулинарные зарисовки at https://www.aynmark.com/archives/130