Wash the zucchini, remove the roots and cut in half lengthways. Peel out the pulp.
Briefly sauté the hollowed out zucchini halves in a little water so that they are soft but still in shape (one to two minutes).
Halve and core the avocados, scoop out the pulp and mash with a fork. Season to taste with salt, pepper, pressed garlic and cayenne pepper.
Roast the pine nuts dry in a pan and add to the avocado mixture. Stir in the quark.
Put the zucchini halves in a baking dish, pour in the avocado mixture and sprinkle with the grated grana. Allow to gratin at 200 degrees for about 20 minutes.