Put the zucchini (courgettes) and shallots in a casserole with 2/3 cup (150 ml/ 1/4 pint) of water.
Cover and microwave on HIGH for 10 minutes.
When the zucchini (courgettes) are cooked, puree the zucchini (courgette) and onion mixture until smooth.
Leave the puree in the bowl of the food processor.
To make the sauce, put the butter in a dish and melt in the microwave oven for 1 minute on HIGH.
Stir in the flour.
Add the milk and stir well.
Cover and micro wave on HIGH for 3 minutes, whisking with a hand beater every minute.
Crumble the 1/2 cube of bouillon (stock) into the sauce.
Pour the sauce into the food processor.
Add salt and pepper to taste.
Puree until smooth.
Taste and adjust seasoning.
Rinse the basil leaves, pat dry on kitchen paper and snip with kitchen scissors.
Pour the soup into 4 plates, sprinkle the basil over