For the Chicken Marinade:

• 600g (1.2 lbs) boneless, skinless chicken thighs, cut into 3cm cubes
• ½ cup plain full-fat yogurt (or Greek yogurt)
• 6 cloves garlic, minced
• 1 tbsp fresh ginger, grated
• 1 tsp garam masala
• 1 tsp ground cumin
• 1 tsp ground coriander
• 1 tsp paprika (sweet or smoked)
• 1 tsp salt
• 1 tbsp vegetable oil
• 2 tsp lemon juice
• ⅛ tsp cayenne pepper (optional, for heat)

For the Curry Sauce:

• 3 tbsp vegetable oil
• 30g (2 tbsp) unsalted butter or ghee
• 1 yellow onion, finely chopped
• 2 tbsp fresh ginger, grated
• 6 cloves garlic, minced
• 1 tbsp paprika
• 2 tsp turmeric
• 1 tbsp garam masala
• 2 tsp ground coriander
• 1 tsp ground cumin
• ⅛ tsp cayenne pepper (optional)
• 400ml (1⅔ cups) tomato passata
• 400ml (1⅔ cups) water
• 100ml (⅓ cup + 1 tbsp) heavy cream
• 1 tsp sugar
• 50g (3 tbsp) unsalted butter or ghee (optional, for richness)

Optional Garnishes:

• Fresh cilantro, chopped
• Lemon wedges