Wash and quarter the potatoes. Peel the shallots and cut them roughly into pieces. Peel the garlic and cut into strips. Put everything on a piece of aluminum foil, season with salt and pepper and drizzle with olive oil. Close the foil and bake the packet in a preheated oven at 160 ° C for about 1 hour.
In the meantime, wash the zucchini, cut into 8 to 10 mm thick slices and fry in olive oil on both sides. Season the zucchini slices with a little salt and pepper, sprinkle with a few herbs and place in an ovenproof dish.
Let the potatoes and shallots cool down briefly. Peel and press the potatoes. Puree the shallots and garlic in a blender and add to the potatoes. Mix with the beaten egg, salt and pepper. Put the potato mixture in a piping bag and spray onto the zucchini slices with the star nozzle. Bake for about 15 minutes at 160 ° C. Serve immediately.