Grate the potatoes and mix with the low-fat quark. Salt and pepper the paste-like mass and season with nutmeg. Spread thinly on baking paper (just so that a closed, rectangular surface is created).
Bake in the preheated oven at 220 ° C until the edges turn brown.
Briefly fry the chopped onions in a little olive oil. Add the spinach and fry briefly. Deglaze with a little water so that the floor is covered with it. Simmer until the spinach is thawed. Then squeeze out the excess water in a sieve (delicious soup mixture). Season with salt and pepper and mix in the cream cheese.
Spread the spinach mixture on the potato platter. Carefully remove from the baking paper with a pan lifter (it is a bit tricky) and roll up.
Now sprinkle the roll with the Gouda cheese and put it in the oven again. Baked until the cheese has melted. Serve immediately.