Mix the diced chicken with yoghurt, lemon juice, cumin, coriander, turmeric, chilli powder, black pepper, salt, garlic puree, and ginger puree. Cover and let it marinate for at least 30 minutes, preferably overnight.
Preheat the oven to 220 ° C or 200 C fan or 425 ° F or Gas 7.
Line a baking tray with parchment paper. Arrange the chicken in a flat layer and place it in the centre of the preheated oven. Bake the chicken for 10-12 minutes until it is just cooked and beginning to brown.
Meanwhile, heat a large pan over medium heat and add the oil. Add cumin seeds and toast until fragrant.
Add the diced onions and cook until softened and golden brown. Stirring occasionally.
Add garlic, ginger, and green chilli, cooking for another minute.
Add the tomato passata and butter. Simmer for 10 minutes, stirring occasionally.
Add the garam masala and fenugreek leaves, then mix well.
Add the cooked chicken to the pan, stirring to coat it in the sauce. Simmer for another 5 minutes, allowing the flavours to mix.
Garnish with fresh coriander and serve hot with basmati rice.
