Preheat your oven to 400°F (200°C) and gather your ingredients.

In a large oven-safe pot, heat a splash of oil over medium heat. Add the chopped onion and sauté for about 5 minutes until soft.

Stir in the curry paste, followed by the chopped tomatoes and coconut milk. Cook for 3-4 minutes until sauce thickens slightly.

Add chicken pieces directly into the pot, ensuring they're submerged in the sauce.

Transfer the pot to the oven and bake for about 60 minutes until chicken is fully cooked and tender.

Add fresh spinach to the pot and stir gently, allowing it to wilt for 2-3 minutes.

Serve over jasmine rice or alongside warm flatbreads.