Preheat oven to 180°C. Grease baking tin and line with puff pastry. I take a round springform pan. Peel onions and cut or slice them thinly. Wash the zucchini and cut or slice into thin round slices.
Heat the oil in a frying pan, lightly salt the onions and courgettes and fry for 7-8 minutes - stirring occasionally. Let the vegetables cool down.
Eggs, cream, ger. Parmesan and chives and season with salt and pepper. Put fried zucchini and onions into the springform pan and spread on puff pastry. Pour egg-cream-cheese mixture over it.
Bake the cake for 35 minutes at 180 °C. Leave to cool, garnish with basil and serve. Bon appetit.