Preheat the oven to 175°C / 350°F.

Thinly slice the courgette with a mandoline. Finely chop the shallots and chives.

Heat the olive oil in a skillet over medium-high heat. Sear the salmon fillet skin-side down until the skin is crisp and the flesh is cooked through.

Transfer the cooked salmon to a mixing bowl. Flake it into small pieces with a fork.

Mix the flaked salmon with crème fraîche, chopped chives, and the juice of 1 lemon. Set the salmon filling aside.

Cook the courgette and shallots in the skillet until golden and tender. Season with salt, garlic powder, and half the zaatar.

Melt the butter in a saucepan and whisk in the wheat flour. Cook the roux for 1 minute.

Gradually whisk the milk into the roux until smooth and thickened. Stir in the zest and juice of 1 lemon and the remaining zaatar.

Spread a thin layer of lemon béchamel in the baking dish. Cover it with lasagna sheets.

Add a layer of cooked courgette and shallots. Spoon over one-third of the salmon filling.

Add another layer of lasagna sheets and béchamel. Repeat the layers until the ingredients are used, making at least four layers.

Cover the final layer with béchamel and shredded mozzarella. Bake for 40 minutes until browned and bubbling.

Rest the lasagna for 10 minutes before serving. Cut into 4 portions.