Salmon and Spinach Casserole

This salmon and spinach casserole is perfect for any occasion! Layers of rich flavor are perfect for a comfort food meal, and you can even make this ahead of time to reheat at the dinner hour. The best part is that this dish is not only healthy but also incredibly tasty. You won’t be able to resist the creamy sauce and delicate flavors of the salmon and spinach.

Making this simple casserole is a great way to use up any leftover salmon or mashed potatoes you may have. If you don’t have any cooked salmon on hand, you can easily cook some fresh salmon fillets or use canned salmon. This recipe is also perfect for meal prepping. You can make a big batch and enjoy it all week long.

If you like spinach, then you might also love our spinach casserole or this super easy spinach and ricotta stuffed pasta casserole. Both are a great way to get that added leafy green into your diet!

white baking dish of salmon casserole on table by bowl of fresh herbs

What Do I Serve With Salmon Casserole With No Pasta?

The best thing about a casserole is that it has everything you need in one dish. This dish has protein, veggies, and a starch, the potatoes, all together in one dish. If you want to add a side dish, I would recommend either a simple side salad or serving more vegetables, like green beans or roasted broccoli.

round white plate of salmon and spinach casserole on white table

Ingredients

3 tablespoons butter (43g)
3 tablespoons flour (23.5g)
2 garlic cloves
1 small white onion
2 tablespoons olive oil (30ml)
1 cup milk (250ml)
10oz frozen spinach (300g)
4 cups prepared mashed potatoes (1kg)
1 pound canned salmon (500g)
2 cups shredded mozzarella cheese (450g)

Useful Kitchen Tools

white baking dish of salmon and spinach casserole with spoon in side of dish

How to Make a Salmon and Spinach Casserole

Video Recipe

This recipe is great for leftovers, but if you do not have leftover mashed potatoes or salmon, you will need to prepare those first. You'll want around 4 cups total prepared mashed potatoes. This is easy to make with instant potatoes, or you can use fresh. Simply mash as you normally would, and season with salt and pepper as desired. Canned salmon is easy, but you can bake/broil/grill fresh salmon with basic seasonings and use here if preferred. You will also need to thaw the spinach and pat it dry.

Now, when you are ready to start cooking, you will preheat the oven to 350°F/180°C and spray your baking dish with non-stick spray. A 10" baking dish is ideal, but you can use a 9"x13" pan if you prefer.

In a large skillet, add the olive oil and butter to melt over medium heat. When the butter has melted, add in the chopped onions and cook them for 5 minutes, stirring regularly.

butter and onions in stainless steel skillet on hot plate

Then, add in the minced garlic and stir while cooking it for another 30-seconds.

Now, add the thawed and dried spinach. Stir this in with the remaining 2 tablespoons of butter.

cooked spinach added to butter and onions in skillet on hotp late

Once the butter has melted, you will add in the flour. Stir it together with the spinach so it coats everything and continue to cook it for another 2 minutes.

Now, you will pour in the milk, stirring it into the spinach and onion mixture until it is combined. Continue cooking this, stirring occasionally, for another 5 minutes until it starts to thicken.

creamed spinach in skillet on black hot plate

Then you will add 1 cup of the shredded cheese to the spinach and stir until it is melted and incorporated. Now, remove from the heat and set this aside.

Now, spread 2 cups of the prepared mashed potatoes onto the bottom of the baking dish. Top it with the creamed spinach mixture.

creamed spinach being poured over mashed potatoes in baking dish

Then, spread the drained salmon over the spinach evenly. Top this with the remaining mashed potatoes.

potatoes being spread over top of salmon and spinach

Finally, sprinkle the remaining 1 cup of cheese over the top of the casserole and bake for 50 minutes.

wooden spoon and cream cloth napkin next to white baking dish of salmon casserole

Frequently Asked Questions

What Type of Salmon Works in a Casserole?

I am using canned salmon or salmon in a pouch. However, you can any type of salmon in this casserole. I usually go for the pre-cooked salmon because it’s easy to find and less expensive than fresh salmon.

If you want to use fresh salmon, you will need to cook it before adding it to the casserole. You can either bake it, poach it, or grill it. The key is to have the salmon cooked before adding it to the casserole.

Can I Use Frozen Spinach in Spinach Casserole?

Yes, you can use frozen spinach in this casserole. I prefer to use frozen spinach because it’s more convenient and less expensive than fresh spinach.

If you want to use fresh spinach, you will need to cook it before adding it to the casserole. You can either sauté it or steam it. Then you will turn it into creamed spinach as directed.

How Long Does Salmon Casserole Last?

This salmon and spinach casserole will last in the fridge for up to four days. You can also freeze it for up to two months. When you’re ready to eat it, let it thaw in the fridge overnight and then reheat it in the oven.

How to Reheat this Casserole

This salmon and spinach Casserole is best reheated in the oven. You can either heat it up from frozen or thawed.

If you’re reheating it from frozen, place it in a baking dish and cover it with foil. Bake it at 350°F for about an hour, or until heated through.

If you’re reheating it from thawed, place it in a baking dish and cover it with foil. Bake it at 350 degrees Fahrenheit for about 30 minutes, or until heated through.

white baking dish filled with salmon and spinach casserole on table by wooden spoon

More Easy Casseroles

If you need more easy casseroles to fill in your meal plan, below are a few more great choices. These are easy to make and sure to satisfy the entire family. Make sure that you bookmark these, print out the recipes, or pin them to Pinterest to make soon!

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