Place the spinach in a large pan with just the water that clings to its leaves after washing. Add a large pinch of salt. Heat gently until the spinach has just wilted, then remove from heat and drain, reserving any liquid.
Either chop the spinach finely using a large knife or place it in a food; processor and process into a fairly course puree.
Heat the oil in a large, heavy saucepan. Add the onion, garlic and chile and cook over low heat, stirring occasionally for 4 - 5 minutes, until softened.
Add the rice and stir until all the grains are well coated, then pour in the stock and reserved spinach liquid. Bring to a boil over medium heat, then lower the heat and simmer for about 10 minutes.
Add the spinach and season with salt and pepper to taste. Cook for 5 - 7 minutes more, until the rice is tender. Check the seasoning and serve in warmed soup plates with the grated Pecorino cheese.