Salt the courgettes and leave to stand in a sieve for approx. 30 mins., then press out all the liquid. Mix the courgettes with the minced meat, onion, garlic and breadcrumbs and season. Knead well by hand until the ingredients form a compact mass. Divide the meat mixture into 18 meatballs and press a well into each. Put a cube of Gorgonzola in each well and smooth the meat over it to form a meatball.
Heat the oil in a non-stick frying pan and fry the balls all over, in batches, over a medium heat for around 4 mins. each. Remove and transfer to a baking tray lined with baking paper.
for approx. 10 mins. in the centre of an oven preheated to 160°C.