Lightly grease and line a 23cm springform tin with 2 sheets of plastic wrap, ensuring there is quite a lot of overhang.

Prepare the trout by removing the skin, and gently removing the bones and discarding. Flake the trout and check for any more small bones. Chill until ready to use.

Place the potatoes and carrots in a medium saucepan of cold salted water and bring to the boil, reduce to medium and cook for 20-25 minutes until tender. Remove using a slotted spoon and set aside to cool slightly. Once the potatoes have cooled, cut into 5mm slices. Place in a small bowl with the mayonnaise, chopped gherkin, gherkin juice, capers, mustard and chives, and stir to combine. Season to taste. Thinly slice the carrots into rounds and set aside.

Bring the saucepan of water back to the boil, gently lower in the eggs with a slotted spoon and cook for 8 minutes. Drain and place in a bowl of iced water to cool completely. Peel once cold and slice in half. Set aside.

Peel and julienne the beetroot and toss with sugar, vinegar and horseradish cream. Set aside.

To make the mascarpone frosting, place all the ingredients in a large bowl and whisk until glossy and thick, being careful not to over mix it as it will turn into butter.

To assemble, use a serrated knife to slice the top off the boule, and trim the crusts off the sides to fit the springform cake tin and slice 2 x 2cm rounds.

Place the first round of bread in the base of the prepared tin, then use a spatula to add a generous dollop of mascarpone mix over the bread and smooth out flat. Top with the trout and season with cracked pepper. Add the potato salad in an even layer, then the eggs face down in a circular pattern. Top with beetroot to fill in between the gaps. Then top with onion, radishes and half the cucumber. Place over the sliced carrots and scatter over the sauerkraut. Finish with the other layer of bread and press down. Bring the edges of the plastic wrap over the top to enclose. Chill in the fridge for at least 1 hour, weighing down with a heavy chopping board.

When ready to serve, remove from the cake pan and remove the plastic wrap. Place on a serving plate. Using an offset spatula, spread the remaining mascarpone frosting over the top and sides of the smögåstärt. Top with remaining cucumber, chives and caperberries. Slice into wedges to serve.