Shell and boil peas in a small amount of salted water. In a large bowl, beat four whole eggs and refrigerate. In a saucepan, bring four cups of water to a boil, add a pinch of coarse salt and rice.
Cook over moderate heat (for about 15 minutes), stirring constantly, until all the water is absorbed. Remove from the heat and quickly fold in the 4 beaten eggs, butter and grated Parmigiano Reggiano.
For the filling, chop the onion. In a large pan, heat oil over medium heat, add onion and cook until translucent, i.e. slightly soft. Add meat and brown. Stir in tomato paste and wine and allow to evaporate. Add a bit of hot water, a pinch of salt and pepper.
Cook for about 20-30 minutes over low heat and cool. Add boiled peas, saffron, cubed cheese and grated caciocavallo. Wet your hands, take a handful of rice and spread on the palm of your hand.
Place a spoonful of filling in the middle and squeeze to seal. You will have a ball the size of an orange with filling inside. Roll the arancini in flour, then in beaten egg and finally in breadcrumbs.
In a pan over medium heat, pour enough oil to cover the arancini and heat (check temperature with a few breadcrumbs). Fry the rice balls until golden, turning at least once. Remove with a big slotted spoon and drain on paper towels. Serve immediately.