Peel and finely chop the onion. Wash the spinach leaves and shake dry. Also wash the salmon and pat dry. Then sprinkle with a little lemon juice and salt and cut into rough cubes. Cut the mozzarella into fine slices.
Heat a dash of olive oil in a large frying pan and sauté the onion until translucent. Add the pine nuts and roast them briefly. Add the spinach leaves and sauté, stirring constantly. Add the ricotta and liquid cream, season with salt, pepper and a pinch of nutmeg and mix thoroughly. Then set aside.
Preheat the oven to 180°/350°F top/bottom heat.
For the béchamel sauce, put the butter in a saucepan and melt over low heat. Then add the flour and stir thoroughly. Now add the milk and bring to the boil. While doing this, whisk thoroughly until a lump-free sauce is formed. Season to taste with salt, pepper and a small dash of lemon juice.
Prepare a small casserole dish per serving and cover the bottom with some béchamel.
Then put a layer of lasagna sheets on top. Now follows a layer with the spinach-ricotta mixture. In this layer spread some of the salmon cubes. Then cover with a little béchamel sauce.
Repeat the previous step and finish with a layer of mozzarella slices.
Now bake the lasagna in the oven for about 30 to 40 minutes until golden brown. Let cool briefly before serving.Buon appetito!