Heat 4 tbsp vegetable oil or butter in a pan over medium heat. Sauté 2–3 finely chopped garlic cloves until fragrant, then add chopped onion and cook until golden brown. Stir in 300g canned chopped tomatoes and simmer for 5 minutes until thickened. In a separate bowl, mix 50g Butter Chicken spice mix with 100ml water to form a paste, then add it to the pan and cook for 2 minutes. Add diced boneless chicken and cook for 10 minutes until fully done. Stir in 250ml single cream and 2 tbsp butter, mix well, and simmer for 2–3 minutes until creamy. Season with salt and set aside.