Cheesy Gratin-Topped Fish Pie Recipe

This easy cheesy gratin-topped fish pie recipe is perfect when time is limited and your energy levels are low. There’s no need to pre-cook the fish, it cooks to perfection in the oven whilst the potato topping is doing its thing.

Serve with some steamed broccoli or asparagus, with some fine green beans or a side salad. 

 If you have any left over you can reheat it in the microwave and have it for lunch tomorrow!


You will need:

  • A 300g (ish!) pack of fish pie mix – they sell them in supermarkets down the fresh fish aisle. The exact amount doesn’t matter too much
  • 300 ml double cream 
  • Salt and freshly ground black pepper (or freshly ground mixed peppercorns)  
  • A handful of freshly washed baby spinach, patted dry (optional) 
  •  A handful or two of grated cheddar cheese   
  • 3 or 4 medium potatoes – peeled if you like but if they’re the washed ones you can leave the skin on if you prefer. Either way is fine!  
  • A little butter


Pre-heat the oven to 190oc or Gas mark 6

Dot a little butter around an oven-proof casserole dish 

For the potato topping

Slice the potatoes into even, fairly fine slices and put in a pan.

Cover the potato slices with cold water and add a little salt.

Bring to the boil and cook until soft.

Prepare the Creamy Fish Base

Whilst the potatoes are cooking you can prepare the fish by adding a little salt and pepper to the cream and stirring well.

Open the fish pie mix and place in the oven-proof dish, mix in some of the now seasoned cream

Sprinkle with spinach (if using) and some of the grated cheese and a little more of the cream

Assemble the Dish

Once the potatoes are cooked, drain carefully. 

Layer the potatoes neatly over the fish and spinach and top with as much cream as you need and more cheese.  

Cook until golden and bubbling

Put in the oven for 25 to 35 minutes or until it looks golden and bubbling and the fish is cooked through.

Variations on this recipe

If you like you can swap the fish pie mix for the same amount of smoked haddock, cut into bite-size pieces and top with the gratin top

Or you could swap the topping for mashed potato but use the same idea with the creamy fish base

You could add prawns to the recipe or add leeks or peas if you like

Cooking Tip:

When boiling potatoes use cold water as it helps the potatoes to cook evenly or you run the risk of the outer edges of the potatoes cooking quicker than the inside.

That said in this recipe you will find that it would probably be ok to use boiling water out of the kettle as the slices are going to be fairly fine with a large surface area

Sarah Cooper

Sarah Cooper

I love cooking! I’m hoping that by sharing some of my cooking wisdom, recipes and tips with you you’ll come to love cooking as much as I do! When I’m not cooking and writing, I love spending time with my family and my cat and reading crime novels

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