Zingy butter chicken curry

Ingredients

• 60 gram butter
• 1 1/2 tablespoon olive oil
• 1 onion, diced
• 750 gram chicken thigh fillets, quartered
• 4 garlic cloves, minced
• 1/2 teaspoon chilli powder
• 1/2 teaspoon ground cumin
• 2 teaspoon ground coriander
• 1 teaspoon ground ginger
• 3 teaspoon garam masala
• 1 3/4 cup tomato passata
• 1/3 cup cream
• 1 1/2 tablespoon sugar
• 1/2 cup greek yoghurt
• sea salt and white pepper
• handful coriander leaves
• small handful pistachios, chopped roughly
• steamed jasmine rice and naan bread, to serve