Place the carrots, celery, half of the onions and water into a large saucepan
Bring the stock to a low simmer and cook for 45 minutes
Add the spinach and simmer for 2 minutes, then blend the stock with a stick blender until smooth
Keep on a low temperature while you start the risotto
Place the oil into a large heavy-based non-stick saucepan and heat over a medium temperature
Add the rest of the onion, lower the temperature and sauté until soft
Add the garlic and continue to cook until soft
Then add the rice and cook, stirring gently, until the rice is covered with oil and starts to go opaque
Pour in the wine and simmer until the wine is nearly all absorbed
Add one ladle of the stock, a pinch of salt and stir to combine
Cook on a low simmer until all of the stock is absorbed
Continue adding the remaining stock a ladle at a time, stirring each time you add some, until the rice is cooked and has just a little bite when tasted
When all of the liquid has been absorbed, turn off the heat and stir in the cheese, zest and butter
Season to taste then set aside to cool
For the arancini
Once the risotto has cooled preheat the oven to 160° Celsius
Place the peas into a bowl and crush with the back of a fork
Add the mint and pesto and stir to combine
Season to taste
Divide the mixture into 10 and flatten the rice on your left hand (if you are right handed)
Place 5mls of the pea and pesto mixture into the middle
Shape the rice into a ball
Set aside until you have done all of them
Dip each ball into the egg white and then into the breadcrumbs
When completely coated, place into a lined baking tin
Once all the balls have been coated place into the oven for 20 minutes