Put the breadcrumbs in a bowl, add the milk, stir and leave to soak for 10 minutes.
In a large bowl, use a spoon to combine the chicken mince with the soaked breadcrumbs, lemon zest, two teaspoons of chopped parsley, a teaspoon of minced garlic, one-third of the parmesan, the egg and a really generous pinch each of salt and pepper.
Heat the oven to 200C (180C fan)/390F/gas mark 6, and line a baking sheet with greaseproof paper or a silicone mat.
Use your hands to spread the oil over the lined sheet, then use the same oily hands to roll the mince mixture into 12 large meatballs weighing about 45 g each.
Arrange the meatballs on the baking sheet as you work, occasionally wiping your hands over the oil to prevent the meat sticking to them and to apply a little oil to the outside of the balls.
Bake for 13 minutes, by which time they will be pale, but set and clearly juicy.
Meanwhile, bring a large pan of generously salted water to a boil.
Drop in the orzo and cook at a steady simmer for a little less than the packet instructions, so it's tender but not swollen.
Strain and save the cooking water.
When the meatballs and pasta are both nearly done, gently melt the butter in a medium saucepan on a low-medium heat, then add the remaining garlic and let it warm through, but not colour, for two to three minutes.
Take off the heat, stir in the remaining parsley, then transfer two tablespoons of the garlic butter mixture to a large bowl.
Tip the orzo into the garlic butter pan, stir in the remaining parmesan, then add the spinach, pour in 200 ml of the reserved pasta water, and shuffle and fold the spinach into the orzo as it wilts.
This should flow like a loose risotto, so add more pasta water as the orzo swells and stiffens.
Tip the cooked chicken balls into the bowl of garlic butter, squeeze over 2 of the lemon segments, and toss gently to coat.
Ladle the orzo into shallow bowls or deep plates and top with meatballs, more parmesan and a segment of lemon to squeeze over while eating.
