Preheat oven (electric stove: 220 °C/circulating air: 200 °C/gas: see manufacturer). Line a baking tray with baking paper. Wash the zucchini. Cut crosswise close together, but not completely through (see tip). Place the zucchini on the baking tray and spread with herb butter. Bake in a hot oven for about 30 minutes, after 15-20 minutes slide the zucchini onto the upper shelf.
For the basil cream, peel and chop the garlic. Wash the basil, shake dry, pluck the leaves and chop finely. Mix sour cream with lemon peel, basil and half of the garlic. Season with salt, pepper and sugar. Cut olives into rings.
For the minced onion peel the onion. Chop the onion finely. Heat oil in a pan. Fry the minced meat in it until crumbly. Add onion, rest garlic, harissa and 1⁄2 tsp paprika and fry briefly. Deglaze with 6-7 tablespoons of water and bring to the boil. Season to taste with a little salt if necessary.
Remove the zucchini from the oven and serve. Spread basil cream over 2 courgettes, sprinkle with olives. Spread the minced meat on the remaining zucchini. Flatbread tastes good with it.
Place two wooden spoons on both long sides parallel next to 1 courgette. Then cut the zucchini à la Hasselback - the stems of the spoon prevent you from accidentally cutting the zucchini completely.