Preheat the oven to 200C/400F/Gas 6 and grease a 28cm/11in pie dish with butter.
For the pastry, mix both flours and the salt together in a large bowl, then rub in the butter with your fingers. Mix in the quark or fromage frais. Knead the dough lightly with your hands just until the ingredients come together (alternatively, put all the ingredients in a food processor and pulse). If the dough does not bind together, add a little water and briefly mix again.
On a lightly floured work surface, roll out the pastry to a circle large enough to line the pie dish. Line the dish with the pastry, then leave it to rest in the refrigerator for an hour.
Cover the pastry case with baking parchment and fill with baking beans or uncooked rice to weigh it down. Bake for 15 minutes. Remove the paper and beans and bake for five minutes more, or until the base looks dry.
To make the filling, rinse the spinach in cold water, then place in a saucepan over a medium heat and allow to wilt. When it’s just wilted, drain really well in a sieve.
Gently fry the shallot in butter for 3-4 minutes without browning. Turn off the heat and add the spinach to the pan.
Beat the eggs in a large bowl, then add the crème fraîche, cottage cheese, nutmeg, salt and pepper and mix well with a wooden spoon. Now add the salmon and spinach mixture and mix again. Season again, to taste, with salt and pepper.
Pour the mixture into the pastry case and bake for 30-35 minutes, or until the filling has set but retains a slight wobble in the centre.
For the kale and pomegranate salad, put the kale in a large bowl with the pomegranate seeds. In a small bowl, whisk together the lime juice, oil, salt and pepper to make a dressing. Pour the dressing over the salad and mix.
Serve the warm tart in slices with the salad alongside.