Place chicken in a large bowl with the yoghurt, lemon zest, cumin, gram marsala and salt and pepper.
Wash the rice and drain. Mix in a large bowl with the garlic, ginger and turmeric.
Heat half the butter in a large fry pan and fry onion until golden, about 15 minutes. Set aside.
Melt the remining butter, remove from the heat and add half the rice, covering the bottom of the saucepan. Arrange the chicken and marinade on top. Add the spinach. Place the cooked onions next.
Cover with the rest of the rice and then pour the stock over the top.
Cover the lid tightly and cook over a low heat for 30 mins without uncovering.
Remove the lid and dry off for 5 mins on the low heat.
Add the sliced almonds and chopped coriander to serve.