Boil potatoes in salted water about 20 - 25 minutes. Cut 2 courgettes into slices, 1 courgette into stripes lengthwise. Cover slices with oil on both sides, season with salt and pepper and sprinkle with parmesan.
Preheat oven to 200°C
Peel potatoes and cool down. From the end of potatoes cut a piece - potatoes must stand.
Halve potatoe, season with a dash of rosmarin, put a courgette slice upon and then the second part of potatoe. Upon the potatoe fix a courgette stripe with a pick.
Place potatoe sticks on a oiled or with baking paper covered baking plate. Gratinate in oven about 25 minutes.