Pre-heat the oven to 180ºC.
Spray a saucepan with low calorie cooking spray and set the pan on a medium heat. Add the leeks and cook for 3 minutes until they start to soften.
Add the cream cheese, double cream alternative, garlic granules, lemon juice and season with salt and pepper.
Take off the heat and add the spinach, stirring the mixture and allowing the spinach to wilt.
Take your ovenproof dish and add the cod fillets. Season with a little salt and pepper.
Pour in the creamy spinach sauce and spread evenly over the top of the cod fillets.
Place the tomato halves over the creamy cod and pop in the oven for 15 minutes.
The cod should be flaky and leeks cooked through. Serve with steamed vegetables or your choice of accompaniment.