Boil the rice and drain it when it is still al dente – firm to the bite. Mix it with the saffron, 3 eggs and have the butter and let it cool. Blanch the peas, drain them and gently sauté them in the remining butter. In a separate pan, soften the finely chopped onion in a little oil, add the ground beef, a little salt and pepper, the whole peeled tomatoes drained and chopped and leave to simmer gently, covered. Once the sauce is ready, mix in the peas. To prepare the rice balls, take a little of the rice mixture and form it into a shell shape, place in the middle the filling of meat and peas, a small cube of the caciocavallo cheese, and cover it with more of the rice mixture to form a ball. Dip the balls completely in flour and then in a beaten egg mixture seasoned with salt, and finally in breadcrumbs. Fry the rice balls in enough oil to fully cover them at a medium-high temperature.