Ready In 90 mins
- Preheat the oven to 200ºC/400ºF/Gas 6.
- Peel, cut, and boil the potatoes until soft (15 mins), then mash with the butter and Rosemary & Garlic Infused Olive Oil. Add a splash of warm milk if needed. Season with salt and pepper, then set to one side and keep warm.
- Melt the butter, then stir in the flour, stock, and milk bit by bit. Bring to the boil, then simmer until thickened (10 mins).
- Check the fish fillets for bones, then cut into chunks and place at the bottom of your baking dish. Pour in the white sauce, add the spinach, then add the mashed potatoes on top. Grate cheese on top if desired.
- Bake in the oven for 45 minutes. The fish should be cooked through, the sauce should be bubbling, and the top should be golden.
- Serve with a drizzle of caramelised onion balsamic.