Apply mustard and spread with a spoon. Leave 2 cm on the edges. Add fried leeks to the mustard, then the grated Parmesan cheese, turn the pages, you can add a little cheese on the folded edges. In the end, spread the green onions and garlic rings, pour the remaining butter on the pan. Finish with black pepper. Bake for 30 minutes or until Galette is golden brown.