Cod, spinach & potato gratin

Sliced Potato (33%) [Potatoes, Sunflower Oil, Dextrose], Cod (23%) (Fish), Water, Whole Milk, Cheddar Cheese (7%) (Milk), Spinach (2%), Cream (Milk), Onion, Rapeseed Oil, Cornflour, Dijon Mustard [Water, Mustard Seeds Spirit Vinegar, Salt], Wheat Flour [Wheat Flour, Calcium Carbonate, Iron, Niacin (B3), Thiamin (B1)], Garlic Puree, Salt, White Pepper, Nutmeg.