Steam spinach and season with creme fraiche, salt and pepper.
In another pan, chop mushrooms, sauté and deglaze with a little soy sauce.
Peel and dice the potatoes and sauté with the mushrooms. Cook for 5 minutes.
In a baking dish, lay out your pastry sheet, brush with cream or milk and top with the spinach and mushroom-potato mixture.
Repeat the process until all the pastry sheets (10 pieces) are used up.
Finally, spread again with a little cream and sprinkle with sesame seeds.
Bake at 180 degrees for 30 minutes and enjoy with yogurt.