Preheat the oven for 200°C.
Peel the potato and cut into relatively thin slices. Cook the slices in boiling salt water for about 5 minutes.
In another saucepan cook the spinach in hot water for about a minute or two. Drain and squeeze out the water.
Line a baking tin with half of the potato slices. Put the spinach on top and sprinkle some grated cheese over it. I used some thin slices of camembert instead of the mozzarella for this layer (just because I didn’t have enough mozzarella) and it was delicious 😉
Cover with the rest of the potato slices and some sliced tomatoes. Sprinkle grated mozzarella cheese on top.
Whisk the egg(s) with the cream and pour over the gratin. Bake for about 20 minutes or until the cheese is brown.
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