With a whisk or a whip mix together 6 egg yolks, 4 sticks room temperature butter and 3 tablespoons sour cream until smooth.

In a cup, mix together 1 tablespoon of vinegar and 1 teaspoon of baking soda.

Add to the mixture and stir until combined. 
To that, add 3 cups flour and mix with hands or the paddle attachment on the mixer. Once mixed, add one more cup flour until just combined. If the dough is too soft, add 1/2 cup more, otherwise don’t.

Divide the dough in 6 pieces, cover and refrigerate for 30 minutes.

After about 15 minutes, start working on the meringue. Recipe below.

Whip 6 egg whites on high speed until slightly frothy, then start adding sugar about 1 tablespoon at a time while continuing to whip. Make sure the bowl and whisk you’re making the meringue with are thoroughly and completely clean and grease free. If there’s any trace of grease or egg yolk, the meringue will not whip up. Whip the meringue for about 10 minutes, or until stiff peaks form and the mixture is thick.

Remove 1 ball of the dough from the fridge and roll it out to about 12 inches on the back of baking sheet (this will make it easy to just slide it off when it’s done baking). To make the edges even, you can set a round 12 inch plate/baking pan and cut around it with a knife. Save the scraps, you will combine scraps from each layer and then form an additional layer at the end.

Spread a good layer of plum butter on the rolled unbaked layer. Top it with 1/7th of the meringue and spread in an even layer. Sprinkle with walnuts and press them into the meringue.

Place in the oven and bake @350F for about 20-22 minutes, or until the top is not dry.

Repeat the above steps with the rest of the dough, plum butter, meringue and walnuts.

Bring milk and salt to a boil in a thick bottomed pot, best if it is non stick. While stirring non stop add the semolina. Cook over medium heat, continuously stirring. Once boiling, continue cooking for 5 minutes.

Remove from heat, stir in sugar until dissolved, cover with plastic wrap and allow to cool to room temperature. The butter and cream need to be the same temperature or the cream will have break easily.

Whip butter until pale and fluffy, about 3-4 minutes. Start adding the room temperature cream while continuing to whip, in 4-5 additions. Be careful not to over whip, or the cream will break.

Whip up the heavy cream with sugar until thick. Do not over-whip, or the cream will separate.

Pick out the best looking cake layer and set it aside. We will use it last, making it the top layer.

Place a dollop of cream in the middle of the cake platter. Top with the first cake layer and press to adhere. Top with 1/6th of the cream and spread it around. Continue stacking and topping with cream until the last layer, which will stay ‘naked’.

Use the sweetened whipped cream to cover the sides of the cake.

Use some chopped nuts to press against the sides of the cake.

Allow the cake to sit in the fridge for 12-24 hours before eating.