Thoroughly rinse the rice in a bowl or sieve with several changes of water until the water runs clear. Drain well. Heat a large pan on the stove, tip in the spices, then dry-fry for about 1 min until they are toasted (not burnt) and beginning to release their aromas. Tip the rice into the pan, stir well over the heat, then pour in 4 mugs of water and add 1 tsp salt.
Bring to the boil, then cover and simmer for 8 mins until the rice is almost tender and the water has been absorbed. Stir in the spinach and peas, then cover and leave for 2 mins so the peas defrost and the spinach just wilts.
Rather than serving a plain pilau with the chicken, boost your vegetable intake by adding some veg to the rice. It is also simpler than making an extra side dish.