Place egg yolks, and mayonnaise into Thermo bowl and blend 4 sec/speed 6. Add gherkins and onion and chop 3 sec/speed 4. Add remaining filling ingredients and blend 6 sec/speed 6. Remove from bowl and set aside. Clean bowl if you want a white ‘frosting’.
Place sour cream and cream cheese into Thermo bowl and blend 10 sec/speed 7. Insert butterfly and whip for 30 sec/speed 4. It should be fluffy and aerated. Remove from bowl and set aside in the fridge until ready to use.
Remove the crusts from all the loaf, including the top, leaving only the bottom crust.
Slice the bread loaf into 3 or 4 layers horizontally.
Spread a little of the frosting onto the serving plate you will use. Stick the bottom layer of loaf onto this plate.
Brush this layer with a generous amount of mineral water. Butter it and then spread with some of the filling. Top with other meats, cheeses, vegetables of choice. Top with next layer and repeat, until all layers of bread are used. Do not overfill the layers between the sandwich as it will make it difficult to cut.
Completely brush the whole sandwich cake with mineral water. Frost it using all the frosting you have and pipe rosettes on the top like you would a cake around the outside circumference. Decorate the top with as many garnishes as you would like.
Arrange individual parsley leaves on the outside of the cake. Garnish the base with cherry tomatoes, and add any other garnishes of choice. Cover and refrigerate for at least 24 hours.
The mineral water helps the consistency become easier to cut and more cake like.