Tart Base:
Mix cornmeal, almond flour, potato fiber, xanthan gum, and salt together in a bowl.
Add the butter to the mixture and work it into the dough until it forms a firm ball.
Grease a tart dish well with butter and press the dough into the dish with your hands. Make sure to press the dough well up the sides of the dish.
Prick the dough with a fork and let it rest in the refrigerator for about an hour.
Pre-bake the tart base for 10-15 minutes at 180 degrees Celsius (356 degrees Fahrenheit) fan oven.
Filling:
Put eggs and milk/cream in a bowl and whisk the mixture together. Season it with a little salt and pepper.
Pour the mixture over the pre-baked tart base.
Thaw the spinach in a pot over low heat until it starts to simmer.
Season the spinach with nutmeg, salt, and pepper.
Cut the salmon fillets into cubes.
Spread spinach and salmon on the tart and sprinkle the surface with grated cheese.
Bake the tart for about 25 minutes or until the egg mixture is set and the tart is beautifully golden.
Serve with a good salad.