Begin by first warming the stock on the stove, with the saffron strands.
In a large pan or pot heat a little olive oil, and sauté off the onions, & garlic.
Once the onion is translucent add the tomato and cook until broken down, add the mushrooms & ham.
Add the Arborio, followed by enough of the stock to cover the rice, stir gently until the stock has been absorbed, then repeat the process another two times.
The rice will have absorbed the stock, and become light and fluffy, with a slight firmness still inside. Finish off with the Grana Padano, and allow to cool.
Once cold enough to handle, begin rolling small size balls, placing a piece of mozzarella in the middle of each.
The starch content of the Arborio rice will ensure the grains stick together sufficiently, therefor there will be no need to add a binding agent.
Combine the egg & the milk together until well incorporated.
Once the balls have been rolled, dust in some plain flour.
Then submerge into the egg wash, and finally into some bread crumbs, these crumbs may be either fine or course, fresh or dried, the option is yours.
Once crumbed, fry off in a bath of hot oil 180c for several minutes till golden brown.