Heat the oil in a large pan over a medium heat. Add the onion and cook, stirring, for about 2 minutes until soft and translucent. Stir in the rice and cook for another 2 minutes.
Turn up the heat and add the wine- it should sizzle as it hits the pan. Cook for about 2 minutes to evaporate the alcohol. Once the liquid has reduced begin adding the hot stock a ladleful at a time over a medium heat, allowing each addition to be absorbed before adding the next and stirring continuously.
The rice should always be moist but not swimming in liquid. The process of adding and stirring should take about 18minutes. Four minutes before the end of the cooking time add the spinach and Gorgonzola.
When the risotto is done remove from the heat and stir in the cold butter. Finish with the Parmesan then season well and serve.