This Portuguese cod and mashed potato casserole is one of those cozy dishes that feels special without being fussy. It combines tender salt cod, creamy mashed potatoes and an irresistible golden topping. The savory onion and garlic filling balances beautifully with the smooth potatoes, making it a comforting choice for Good Friday, Easter, Christmas or a relaxed Sunday family lunch.
What Is Portuguese Cod and Mashed Potato Casserole?
This traditional Portuguese dish comes from Porto and is built around soaked salt cod, onions, garlic, creamy mashed potatoes and a mayonnaise topping. Once assembled, it goes into the oven until the top turns golden and lightly browned. The result is rich and creamy inside with a gratin style finish on top, which is exactly what makes this cod casserole so memorable.
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Why You’ll Love This Recipe
- It brings together classic Portuguese flavors
- It is creamy inside with a golden baked topping
- It is perfect for holidays and special dinners
- It can be assembled ahead of time
- It is a complete, comforting main dish
Ingredients and Substitutions
The ingredients in this Portuguese cod casserole work together to create a creamy, balanced and deeply savory dish. Each part matters: the salt cod brings character, the mashed potatoes add comfort and the onion and garlic filling gives the casserole its warm aroma. Here is what you will need to make this baked Portuguese classic at home.
- Salt cod: the main ingredient. You can use frozen soaked salt cod if available.
- Milk: used to cook the cod and enrich the mashed potatoes.
- Potatoes: the base of the mashed potato layer that gives the casserole structure.
- Onion: adds a naturally sweet flavor to the sautéed filling.
- Garlic: adds aroma and boosts the flavor of the cod.
- Olive oil: essential for the traditional Portuguese style sauté.
- Bay leaves: add aroma and depth to the dish.
- Butter: makes the mashed potatoes richer and creamier.
- Heavy cream or table cream: helps create a smooth mashed potato texture.
- Mayonnaise: creates the signature golden topping.
- Olives: used to garnish and finish the casserole.
- Salt and black pepper: bring out the flavors in the dish.
See the recipe card at the bottom of the page for exact amounts.
How to Prepare the Salt Cod
Before cooking, the salt cod should be properly soaked to remove excess salt. This gives the fish a balanced flavor and a more delicate texture. Then simmer the pieces in warm milk for a few minutes. This makes the cod tender and creates a flavorful milk that will be used to enrich the mashed potatoes.
How to Make It
- Cook the cod: simmer the salt cod in the milk until tender, then reserve the milk for the mashed potatoes.
- Flake the cod: remove the skin and bones, then flake the cod into medium pieces.
- Sauté the cod: cook the onion, garlic and bay leaves in olive oil. Add the flaked cod and stir gently.
- Boil the potatoes: meanwhile, cook the potatoes in water until very tender.
- Make the mashed potatoes: mash the potatoes with butter, cream and some of the reserved cod milk until creamy.
- Assemble the casserole: spread a layer of mashed potatoes in the dish, add the sautéed cod and cover with mayonnaise. Finish with more mashed potatoes and olives.
- Bake until golden: bake at 350°F until the top is golden and lightly browned.
- Finish and serve: remove from the oven, let it rest for a few minutes and serve warm.
Serving idea: serve with plain white rice or a fresh green salad.
Variations
The traditional version is made with mashed potatoes and a golden mayonnaise topping, but you can still adjust the casserole to fit your taste. Small changes can bring in new flavors and textures while keeping the spirit of this classic Portuguese cod dish.
- With carrot: add grated carrot to the sautéed filling for a lightly sweet flavor.
- With a cheesy topping: mix Parmesan into the top layer for deeper browning.
- With sweet potatoes: replace part of the potatoes with sweet potatoes for a different flavor.
- Lighter version: use light mayonnaise and a lower fat cream.
Tools and Equipment
Using the right tools makes this Portuguese cod casserole easier to prepare and helps you get a more even result. Good tools also help keep the cod pieces intact and make the mashed potatoes smoother.
- Large pot
- Medium saucepan
- Large skillet or sauté pan
- Potato masher
- Wooden spoon
- Baking dish
For this recipe, I use a medium saucepan to simmer the cod in milk and a large pot to cook the potatoes evenly. Then I use a skillet or sauté pan to cook the cod filling without breaking it up too much. Finally, a potato masher helps make the potatoes smooth, and a baking dish holds the layers while the casserole browns in the oven.
In my shop, you’ll find kitchen tools and equipment I use at home.
Storage
Store the cod casserole in an airtight container in the refrigerator for up to 3 days. This helps preserve the flavor and texture. To reheat, place it in a 325°F oven until heated through. You can also freeze it for up to 2 months.
Tips
- Use good quality salt cod for the best flavor.
- Do not discard the milk used to cook the cod.
- Mash the potatoes while they are still hot for a smoother texture.
- Spread the mayonnaise evenly so the topping browns nicely.
Frequently Asked Questions
Yes. Just make sure it has been properly soaked and desalted before cooking.
Yes. You can use heavy cream mixed with cheese for gratinating.
Yes. Assemble the baking dish and store it in the refrigerator for up to 24 hours before baking.
More Recipes
Looking for more recipes like this? Try these:
Recipe
Portuguese Cod and Mashed Potato Casserole
Equipment
- 1 Large pot
- 1 Medium saucepan
- 1 Large skillet or sauté pan
- 1 Potato masher
- 1 Wooden spoon
- 1 Baking dish
Ingredients
- 2 cups whole milk
- 2 large pieces soaked salt cod about 1 ½ lb total
- olive oil as needed
- 2 onions chopped
- 5 garlic cloves minced
- 2 bay leaves
- black pepper to taste
- 4 ½ lb potatoes
- 1 tablespoon butter
- ¾ cup heavy cream or table cream
- salt to taste
- mayonnaise as needed for topping
- olives for garnish
Instructions
- Start by simmering the pieces of soaked salt cod in the milk until tender. This seasons the fish gently and creates a flavorful milk that will be used in the mashed potatoes.
- Remove the cod from the milk, take off any skin and bones, then flake it into medium pieces. Reserve the cooking milk.
- Meanwhile, boil the potatoes in water until completely tender. Drain and mash them while still hot until smooth.
- Make the mashed potatoes by mixing the potatoes with butter, cream, salt and some of the reserved cod milk. Stir over low heat until creamy and smooth.
- In another pan, heat olive oil and sauté the onions, garlic and bay leaves until soft and fragrant. Add the flaked cod and stir gently. Season with black pepper and adjust the salt only if needed.
- To assemble, spread a layer of mashed potatoes in the bottom of a baking dish. Add the cod mixture, spread mayonnaise over the top and finish with the remaining mashed potatoes. Garnish with olives and bake at 350°F.
- Bake until the top is golden and lightly browned. Serve right away.
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