For the zucchini mushroom toast, preheat the oven to 200 degrees top/bottom heat. Line a baking tray with baking paper. Grate the zucchini with the skin, chop the onion and slice the mushrooms. Cut the ham into small pieces.
Heat some oil in a pan and fry the onion. Then add the zucchini, mushrooms and ham and sauté. Season with basil, marjoram, salt and pepper. Let it cool down a bit.
Mix in creme fraiche and cheese and spread on toast slices. Bake in the oven for about 15-20 minutes, until the cheese gets some color and the zucchini mushroom toast is crispy.