Cut the chicken into rough chunks. Place 300g yoghurt and ground cumin in a bowl and stir to combine. Add in the chicken and stir to coat. Cover and refrigerate overnight.

Heat vegetable oil in a large heavy based pot over medium heat. Add cumin seeds and stir until fragrant, around 30 seconds.

Add in the grated onion and garlic to the pot, and cook until softened, around 5 minutes. Add in ground ginger, ground turmeric and garam masala and stir to combine.

Add the tin of tomatoes and cook, stirring for 5 minutes.

Add the chicken to the pot, along with chicken stock. Simmer without lid, stirring occasionally for 25-30 minutes, until the chicken is cooked.

Whilst curry is cooking, cook couscous according to packet directions. Fluff up with forks and stir through chopped parsley.

When the curry is ready, stir in the baby spinach leaves until just wilted and remove from heat.

Serve curry with couscous, and remaining yoghurt.