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A fish pie with some scooped out with spoon and some fish on a table

Easy Fish Casserole

This simple dish can be made ahead of time and is beyond very easy to whip up into the most creamy, filling and decadent homemade Fish Casserole.
Course Main Course
Cuisine gluten free, Western
Prep Time 5 minutes
Cook Time 40 minutes
Total Time 45 minutes
Servings 4
Calories 304kcal


  • 2 lbs (1kg) potatoes, peeled and cut chunks
  • 4 tbsp dairy-free butter divided
  • 2 cups (500ml) plant-based milk 1/4 cup for mashed potatoes; 1 3/4 cups for casserole.
  • 2 tsp olive oil
  • 2 green onions finely sliced
  • 4 tsp (20g) cornstarch
  • 1 tsp Dijon mustard
  • 1/4 tsp ground nutmeg
  • 4 anchovy fillets finely chopped
  • 1 1/2 cups (400g) fish pie mix
  • 2 1/2 cups (75g) baby spinach roughly chopped
  • 1/2 cup (75g) frozen peas


  • Preheat the oven to fan-assisted 180C / 200C / 400F / gas 6.
  • Add the potatoes into some salted boiling water, bring back to the boil, reduce to a simmer cook until tender.
  • When done, drain, let cool for a few mins and mash with a 4 tbsp of milk and 2 tbsp of dairy-free butter and set aside.
  • Melt butter in a sauce pan, add green onions and cook for a min, then add in cornstarch and cook for a min.
  • Slowly whisk in the milk, then bring to a rolling simmer while stirring continuously (to avoid any lumps) for 3 - 4 mins until the sauce is thick.
  • Switch off the heat, then stir in mustard, nutmeg, anchovies, fish pie mix, baby spinach and peas before transferring mix to a baking dish.
  • Top with the mashed potatoes and bake for 25 mins in the hot oven until golden and the mixture is bubbling.


Fish Casserole Tips

  • If you are starting with whole fish, then make sure to cut into similar-sized chunks.
  • Try adding some shrimp to the fish pie mix.
  • If you have less fish than the recipe calls for, you can bulk up your casserole with extra veggies.
  • Feel free to add more quick-cooking vegetables like green beans and sweetcorn.


Calories: 304kcal | Carbohydrates: 15g | Protein: 26g | Fat: 15g | Saturated Fat: 4g | Cholesterol: 63mg | Sodium: 185mg | Potassium: 663mg | Fiber: 1g | Sugar: 8g | Vitamin A: 2240IU | Vitamin C: 15mg | Calcium: 194mg | Iron: 1.5mg