Remove the frozen salmon and spinach from the ice cream.
Peel and quarter the potatoes and bring to the boil in a saucepan with salted water. Peel the butternut squash and cut into approx. 5 mm thick slices, remove the stones.
After about 5 minutes of boiling potatoes, add the pumpkin slices and bring the water to the boil again for 10 minutes. Pour off the cooking water and let the contents cool down.
Peel and chop the onion and fry in coconut oil until translucent. Put the peeled and finely chopped garlic cloves with the spinach leaves in the pan and boil the liquid to remove the moisture from the spinach. Season to taste with salt, black pepper from the mill, tarragon, thyme and nutmeg.
Preheat the oven to 200 ° C top / bottom heat.
Grease a baking dish with coconut oil. The half-frozen salmon, best carefully slice lengthways, so that it later covers a layer of the casserole.
Cut the potatoes into 5 mm thick slices and cover the bottom of the baking dish with potatoes and pumpkin alternately, like a mosaic. Then the spinach mixture is layered and lightly flaked with parmesan. The third layer consists of frozen salmon drizzled with lemon juice. Put another colorful potato and pumpkin mosaic on the salmon.
Whisk the egg, gratin cheese and the sweet cream together and then spread over the potato and pumpkin mosaic.
Place the casserole dish on the middle rack in the oven and bake for about 30 minutes until the cheese and cream layer is golden brown and crispy.