Cheesy Salmon and Mashed Potato Casserole
Cheesy Salmon and Mashed Potato Casserole
Turn Leftover Salmon and Mashed Potatoes into a Delicious Family Dinner
Have leftover salmon and mashed potatoes sitting in your refrigerator? Don't let them go to waste! This creamy, cheesy salmon and mashed potato casserole is one of those wonderfully simple recipes that turns yesterday's leftovers into a delicious, comforting meal everyone will look forward to.
Made with tender flakes of salmon, creamy mashed potatoes, mixed vegetables, a handful of shredded cheese, and a few pantry seasonings, this easy casserole comes together in minutes. Everything is gently mixed in one bowl, topped with cheese, and baked until beautifully golden and bubbling.
And the best part? You don't even need leftover salmon to make it! Canned salmon works just as well, and those half-empty bags of frozen peas, corn, or mixed vegetables hiding in your freezer are perfect for this dish.
It's an economical, flexible, no-fuss recipe that makes enough for one generous family casserole or two smaller dishes. Enjoy one for dinner and save the other for another day, or share it with someone who could use a homemade meal.
Serve it with a crisp green salad and a generous spoonful of homemade green tomato relish.
What to Serve with Cheesy Salmon and Mashed Potato Casserole
This creamy, cheesy casserole is delicious on its own, but I particularly love serving it with a crisp green salad and a generous spoonful of my Homemade Green Tomato Relish.
The sweet and tangy relish is a wonderful contrast to the rich mashed potatoes, tender salmon, and melted cheese. In fact, after tasting them together, I think they were made for each other!
You could also serve this casserole with homemade ketchup, a squeeze of fresh lemon, or your favourite pickles for a little extra acidity.
Try my Homemade Green Tomato Relish recipe! It's a delicious way to use up the last green tomatoes of the season and makes a wonderful accompaniment to so many family meals.
Why You'll Love This Cheesy Salmon and Mashed Potato Casserole
It's the ultimate leftover makeover.
Leftover mashed potatoes and cooked salmon become something entirely new. Instead of simply reheating yesterday's dinner, you're turning it into a hearty, cheesy casserole with a golden topping and a wonderfully creamy interior.
It's a true freezer-and-pantry meal.
No need to run to the grocery store! Use canned salmon, frozen vegetables, whatever shredded cheese you have available, and a few everyday seasonings. This recipe is about making the most of what's already in your kitchen.
It's incredibly easy to prepare.
There's no layering, no complicated sauce, and no special technique required. Simply combine the ingredients in a large bowl, mix gently without overmixing, transfer to a casserole dish, sprinkle with cheese, and bake at 375°F (190°C) for about 30 minutes.
It's easy to customize.
Don't have peas and corn? Try broccoli, carrots, spinach, or your favourite mixed vegetables. No cheddar? Use mozzarella, Monterey Jack, or a combination of cheeses. You can even add finely diced grey shallots for a little extra flavour, as I do.
It's creamy, cheesy comfort food.
The mashed potatoes hold everything together while keeping the casserole soft and creamy. Tender salmon, sweet vegetables, and melted cheese create a satisfying meal, finished with a beautifully golden crust.
It's budget-friendly and perfect for sharing.
This recipe makes a generous amount without requiring expensive or unusual ingredients. Divide it between two smaller casserole dishes and you've got dinner for tonight and another meal to freeze or give away.
Make It Your Own: Easy Ingredient Substitutions
One of the things I love most about this recipe is that you don't have to follow it to the letter. Think of the ingredients as a starting point and work with what you have.
Salmon: Use leftover baked, grilled, or poached salmon, or well-drained canned salmon. Just make sure it's cooked before adding it to the mixture.
Mashed potatoes: Homemade leftovers are ideal, but freshly made or instant mashed potatoes work too. Aim for approximately 4 cups, or enough to keep the mixture creamy.
Vegetables: Frozen peas, corn, carrots, green beans, broccoli, or mixed vegetables are all excellent choices. Fresh vegetables work too; cook firmer vegetables until tender before adding them.
Cheese: Cheddar, mozzarella, Monterey Jack, Colby, or whatever combination you have in the refrigerator.
Shallots: Finely diced raw grey shallots add a lovely, subtle zing. Regular shallots work beautifully too, or simply leave them out.
Seasonings: Onion powder, paprika, black pepper, and parsley are my favourites, but feel free to experiment with dill, chives, or a little smoked paprika.
Optional crunchy topping: For a little extra texture, sprinkle crushed buttery crackers over the cheese before baking.
A little kitchen tip: If your leftover mashed potatoes are particularly thick or stiff, stir in a splash of milk or cream to loosen them before combining everything. The finished casserole should be creamy, not dry.
Cheesy Salmon and Mashed Potato Casserole
Prep Time: 15 minutes
Cook Time: 30 minutes
Total Time: 45 minutes
Yield: 1 large casserole or 2 smaller casseroles
Servings: Approximately 6–8
Ingredients
2 cups cooked salmon, cubed or flaked (leftover or canned, drained)
4 cups mashed potatoes, preferably leftover
2 cups or more frozen mixed vegetables, such as peas, corn, and carrots, or chopped, cooked fresh vegetables
1½ cups shredded cheese of your choice, divided (1 cup for the mixture and ½ cup for topping)
1–2 grey shallots, finely diced (optional)
1 tsp salt, or to taste
1 tsp ground black pepper, or to taste
1 tsp onion powder
1 tsp paprika or smoked paprika
Fresh or dried parsley, to taste
Instructions
Preheat the oven. Set your oven to 375°F (190°C). Lightly grease one large casserole dish or two smaller baking dishes.
Combine the ingredients. In a large mixing bowl, add the mashed potatoes, cooked salmon, vegetables, 1 cup of shredded cheese, finely diced raw grey shallots (if using), salt, black pepper, onion powder, paprika, and parsley.
Mix gently. Fold everything together until just combined. Avoid overmixing so the salmon retains some texture and the casserole stays creamy.
Fill the baking dish. Transfer the mixture to your prepared casserole dish or divide evenly between two smaller dishes. Spread gently into an even layer.
Add the cheese topping. Sprinkle the remaining ½ cup of shredded cheese evenly over the casserole. Add a little extra parsley if desired.
Bake. Place in the preheated oven and bake uncovered for approximately 30 minutes, or until heated through to the centre and the cheese is melted and beautifully golden. A cold or particularly deep casserole may need additional time.
Serve. Let rest for about 5 minutes before serving. Enjoy with a fresh green salad and homemade green tomato relish or ketchup.
Recipe Notes
Use what you have: This recipe is wonderfully flexible. Canned salmon, leftover cooked salmon, frozen vegetables, and whatever cheese you have in your refrigerator all work well.
Adjust the potatoes: Four cups of mashed potatoes give the casserole its creamy texture, but you can adjust the quantity depending on your leftovers. Aim for a little more mashed potato than salmon.
Keep it creamy: If your mashed potatoes are particularly stiff, add a splash of milk or cream before mixing everything together.
Season to taste: Leftover mashed potatoes, canned salmon, and cheese may already contain salt. Taste the cooked components and adjust the seasoning as needed.
Optional crunchy topping: For extra crunch, sprinkle ½ cup crushed Ritz crackers mixed with 1 tablespoon melted butter over the casserole along with the cheese.
Make ahead and freeze: Assemble the casserole, cover tightly, and refrigerate for up to 24 hours before baking. Alternatively, freeze an unbaked casserole for up to 2–3 months for best quality. Thaw overnight in the refrigerator before baking, allowing additional time if necessary to heat through completely.
Storage: Refrigerate leftovers promptly in an airtight container and enjoy within 3–4 days.
Cheesy Salmon and Mashed Potato Casserole
A creamy, cheesy salmon and mashed potato casserole made with leftover or canned salmon, vegetables, and simple pantry ingredients. An easy, budget-friendly family dinner with a golden cheese topping.
Ingredients
- 2 cups cooked salmon, cubed or flaked (leftover or canned, drained)
- 4 cups mashed potatoes, preferably leftover
- 2 cups or more frozen mixed vegetables, such as peas, corn, and carrots, or chopped, cooked fresh vegetables
- 1½ cups shredded cheese of your choice, divided (1 cup for the mixture and ½ cup for topping)
- 1–2 grey shallots, finely diced (optional)
- 1 tsp salt, or to taste
- 1 tsp ground black pepper, or to taste
- 1 tsp onion powder
- 1 tsp paprika or smoked paprika
- Fresh or dried parsley, to taste
Instructions
- Preheat the oven. Set your oven to 375°F (190°C). Lightly grease one large casserole dish or two smaller baking dishes.
- Combine the ingredients. In a large mixing bowl, add the mashed potatoes, cooked salmon, vegetables, 1 cup of shredded cheese, finely diced raw grey shallots (if using), salt, black pepper, onion powder, paprika, and parsley.
- Mix gently. Fold everything together until just combined. Avoid overmixing so the salmon retains some texture and the casserole stays creamy.
- Fill the baking dish. Transfer the mixture to your prepared casserole dish or divide evenly between two smaller dishes. Spread gently into an even layer.
- Add the cheese topping. Sprinkle the remaining ½ cup of shredded cheese evenly over the casserole. Add a little extra parsley if desired.
- Bake. Place in the preheated oven and bake uncovered for approximately 30 minutes, or until heated through to the centre (165°F / 74°C) and the cheese is melted and beautifully golden. A cold or particularly deep casserole may need additional time.
- Serve. Let rest for about 5 minutes before serving. Enjoy with a fresh green salad and homemade green tomato relish or ketchup.
Notes
Use what you have: This recipe is wonderfully flexible. Canned salmon, leftover cooked salmon, frozen vegetables, and whatever cheese you have in your refrigerator all work well.
Adjust the potatoes: Four cups of mashed potatoes give the casserole its creamy texture, but you can adjust the quantity depending on your leftovers. Aim for a little more mashed potato than salmon.
Keep it creamy: If your mashed potatoes are particularly stiff, add a splash of milk or cream before mixing everything together.
Season to taste: Leftover mashed potatoes, canned salmon, and cheese may already contain salt. Taste the cooked components and adjust the seasoning as needed.
Optional crunchy topping: For extra crunch, sprinkle ½ cup crushed Ritz crackers mixed with 1 tablespoon melted butter over the casserole along with the cheese.
Make ahead and freeze: Assemble the casserole, cover tightly, and refrigerate for up to 24 hours before baking. Alternatively, freeze an unbaked casserole for up to 2–3 months for best quality. Thaw overnight in the refrigerator before baking, allowing additional time if necessary to heat through completely.
Storage: Refrigerate leftovers promptly in an airtight container and enjoy within 3–4 days.
