1. Place the potatoes in a large pot of cold water and bring to a simmer. Simmer for 20-25 minutes until the potatoes are cooked through. Drain and cool, then remove the skins and cut the potatoes into ½-cm-thick slices. Heat a large frying pan over medium heat and add ½ tbsp of butter. Fry the onion with a pinch of salt until translucent and remove from the pan. Add another ½ tbsp of butter and fry the spinach with a pinch of salt until wilted.

2. Heat your oven to 200°C. Grease a 25cm x 35cm baking dish with a little butter and layer a third of the potatoes at the bottom. Cover with a layer of half the onion, then half the spinach, then a layer of both kinds of salmon. Season with salt and white pepper, scatter half the dill on top, then repeat with layers of potato, onion, spinach, salmon and dill. Top with the remaining third of the potatoes.

3. Mix eggs, milk and cream with ½ tsp of salt and a little white pepper. Pour over the assembled pudding and bake for 30 minutes until the top is golden and the eggs are set. Add the remaining butter to a small saucepan and heat over medium heat until the butter is browned and nutty. Pour the brown butter over the pudding and serve with lemon wedges and a green salad. 

Adam's tip For a different version of this laxpudding, add salmon roe to the top as you serve, or even try it with a mixture of salted or smoked cod and fresh fish such as ling. The mixture of the cured or smoked fish and fresh fish gives the dish a little more interest.

For another Scandinavian salmon dish, try Adam Liaw's salmon with pickled cucumbers and Danish potato salad.