Keto Tuna Casserole

What Is Tuna Casserole?

Tuna casserole is an old classic casserole made up of cream of mushroom soup, noodles, tuna, and perhaps a few vegetables. I’ve upgraded the original to add vegetable noodles and made a homemade sauce that is much more flavorful than anything you’ll find in a can.

Is Tuna Casserole Healthy?

Tuna casserole is not necessarily known as a health food. But this recipe is changing all of that! By swapping out the noodles for vegetable noodles, a homemade sauce made without thickeners, and making a crunchy topping without the crackers, we’ve given this a healthy makeover.

Ingredients & Substitutions

Here I explain the best ingredients for my keto tuna noodle casserole recipe, what each one does, and substitution options. For measurements, see the recipe card.

• Olive Oil – Or avocado oil.
• Yellow Squash – Spiralize it to make noodles for the casserole. You have a few options for other “noodles” below.
• Sea Salt & Black Pepper
• Onion – I used a white onion, but you could also use a yellow onion if you prefer.
• Green Bell Pepper – Adds nice crunch and color to the casserole, instead of the traditional green peas. (If you are low carb, depending on your macros, you may be fine with using actual peas here instead.) Also, feel free to saute some mushrooms and add them to the casserole along with the green peppers.
• Garlic – Use fresh minced garlic for best flavor or jarred for convenience.
• Chicken Broth – Use store-bought for convenience or make your own chicken broth. You could also use vegetable broth to make this dish pescatarian, or bone broth for a deeper flavor and nutrition benefits.
• Heavy Cream – Gives the sauce a creamy texture and flavor. Full-fat coconut milk is fine to substitute if that’s what you have on hand.
• Parmesan Cheese – Use grated parmesan cheese in both the sauce and the topping. In the sauce, the parmesan acts as a thickener, but you can also thicken with cream cheese, xanthan gum, or other cornstarch substitutes if you prefer. Softer cheeses, such as mozzarella or cheddar cheese, don’t generally work as well for thickening this sauce, but you can stir them directly into the casserole if you like.
• Tuna – You’ll need 3 5-ounce cans tuna. I prefer solid white albacore tuna for the best texture in a casserole. If you’re not a fan of tuna, feel free to substitute canned salmon instead. You can also use leftover grilled tuna steak to make this recipe as well.
• Crushed Pork Rinds – These are used for the topping, in place of a crunchy chip or cracker topping that you might find in a traditional tuna casserole recipe. You can make your own pork rinds or buy them. Either way, blitz them in a blender to make the consistency of breadcrumbs.

Noodle Variations

This low carb tuna casserole is made with yellow squash, but you can use all kinds of low carb pasta alternatives! Here is how to use the most common ones:

• Zucchini Noodles – You’ll prepare the zucchini noodles the same way you would the squash noodles. They are very similar in taste and texture.
• Shirataki Noodles – Follow my shirataki noodles method for noodles that have a nice bite and aren’t soggy. After the stir fry step, you can transfer them to the baking dish.
• Keto Egg Noodles – Prepare keto pasta and right after you take it out of the boiling water, transfer to the baking dish and top with sauce.
• Cauliflower Rice – After you saute the cauliflower rice, you can add it to the baking dish.
• Spaghetti Squash – Roast spaghetti squash in the oven, remove the strands with a fork, then add to the casserole dish and top with sauce.

How To Make Keto Tuna Casserole

I have step-by-step photos here to help you visualize the recipe. For full instructions with amounts and temperatures, see the recipe card.

1. Cook noodles. Heat olive oil in a large skillet over medium-high heat. Add spiralized squash and season with sea salt and pepper. Sauté until crisp-tender and transfer to a colander over the sink to drain.
2. Sauté aromatics. Start by sauteing the onions until translucent. Add the green pepper and garlic. Cook until starting to brown.

TIP: Ensure the noodles cook down sufficiently to avoid a watery casserole.

You want them to keep the heat high enough to cook away the extra moisture. The end result should be tender, but not super mushy.

3. Make sauce. Add chicken broth to scrape up any brown bits from the bottom of the pan. Bring to a boil then simmer until reduced.
4. Make it creamy. Reduce to low and stir in heavy cream and parmesan cheese. Stir until sauce is smooth. Gently stir tuna into sauce.

5. Assemble. Gently press noodles in the colander to drain excess water. Transfer to the baking dish. Pour sauce, tuna, and vegetables over the noodles and use tongs to coat. (Alternatively, you can mix the casserole ingredients in a large bowl first and then transfer to the baking dish.)
6. Add topping. In a small bowl, mash together more parmesan cheese, pork rinds, and olive oil. Crumble the mixture over the casserole.
7. Bake. Bake the low carb tuna casserole until bubbly. Then, broil for a few minutes to brown the topping.

More Easy Keto Casserole Recipes

If you like this healthy tuna casserole from scratch, you might also like these other keto casserole recipes:

Keto Cheeseburger Casserole

Chicken Bacon Ranch Casserole

Chicken Divan Casserole

Crock Pot Keto Taco Casserole