Healthy Keto Tuna Casserole

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This low carb keto tuna casserole is a makeover version of the classic casserole, but with a few healthy and low carb twists. We’re swapping out the noodles for squash noodles, canned soup for a delicious homemade sauce, and a crunchy topping that doesn’t require crackers! It may be a healthy tuna casserole, but it’s so delicious that no one will mind — and I’ll bet you’ll enjoy this one even if you aren’t keto.

This low carb casserole recipe is just one of 100 you’ll find in the Easy Keto Carboholics’ Cookbook — it’s focused high-carb favorites you might miss on a keto lifestyle, transformed to be low carb! Learn how to make fluffy, chewy breads, delectable desserts, fried foods, and delicious swaps for potatoes, rice, and pasta… all keto friendly with easy ingredients. And even though I decided to publish this keto pasta casserole on the blog, the vast majority of the recipes (75%!) are unique to the book and not found anywhere else.

Baking dish of keto tuna casserole with Wholesome Yum book.

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.

Why You’ll Love This Keto Tuna Casserole Recipe

  • Creamy, cheesy flavor
  • Tender squash noodles
  • Easy to make
  • Simple ingredients
  • Just 4 grams net carbs per serving
Healthy tunna casserole with serving spoon.

Ingredients You’ll Need

This section explains how to choose the best ingredients for keto tuna noodle casserole, what each one does in the recipe, and substitution options. For measurements, see the recipe card below.

  • 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 – Adds flavor to the sauce. 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.
  • 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.
Healthy tuna casserole ingredients.
Noodle Variations

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 egg noodles and right after you take them out of the boiling water, transfer them 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 Healthy Tuna Casserole

This section shows how to make keto tuna casserole, with step-by-step photos and details about the technique. For full instructions, see the recipe card below.

  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.

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.

Noodles for low carb tuna casserole in a skillet.
Skillet with sauteed onions and peppers.

  1. 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.
  2. Make it creamy. Reduce to low and stir in heavy cream and parmesan cheese. Stir until sauce is smooth. Gently stir tuna into sauce.
Aromatics with reduced chicken broth in skillet.
Creamy keto tuna casserole sauce.

  1. 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.)
  2. Add topping. In a small bowl, mash together more parmesan cheese, pork rinds, and olive oil. Crumble the mixture over the casserole.
  3. Bake. Bake the low carb tuna casserole until bubbly. Then, broil for a few minutes to brown the topping.
Assembling low carb tuna casserole.
Baked keto tuna casserole.

Storage Instructions

  • Store: Keep leftover keto tuna noodle casserole in the fridge for 3-4 days. (Freezing is not recommended.)
  • Meal prep: Make sauce and prep noodles. Assemble and bake right before serving.
  • Reheat: Reheat in a 350 degree F oven for best results. Microwaving can work, but the noodles will be more mushy.
Baking dish of healthy tuna casserole.

More Easy Keto Casserole Recipes

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

Reader Favorite Recipes

The recipe card is below! Readers that made this also viewed these recipes:

The Wholesome Yum Easy Keto Carboholics' Cookbook

This reader favorite recipe is included in The Wholesome Yum Easy Keto Carboholics’ Cookbook! Inside this beautiful hard cover keto recipe book, you’ll find 100 delectable, EASY keto recipes to replace all your favorite carbs: bread, pasta, rice, potatoes, desserts, and more… each with 10 ingredients or less! Plus, a photo, macros, & tips for every recipe.



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Tap on the times in the instructions below to start a kitchen timer while you cook.

  1. Preheat the oven to 400 degrees F (204 degrees C).

  2. Heat 2 tablespoons of the olive oil in a 12-inch skillet over medium-high heat. Add the yellow squash and season with salt and pepper. Sauté for 3 to 5 minutes, mixing occasionally with tongs, until crisp-tender. Transfer squash noodles to a colander over the sink.

  3. Add the onion to the pan and decrease heat to medium. Sauté for about 5 minutes, until translucent.

  4. Add the bell pepper and garlic. Sauté for about 5 minutes, until peppers and onions are starting to brown.

  5. Add the chicken broth. Use a wooden spoon to scrape the browned bits from the bottom of the pan. Increase heat to bring the liquid to a boil, then reduce heat and simmer for 3 to 5 minutes, until the liquid volume is reduced by half.

  6. Reduce heat to low. Stir in the heavy cream and 1 1/2 cups of the Parmesan, until the cheese melts and sauce is smooth.

  7. Gently stir the tuna into the sauce.

  8. Gently press on the noodles in the colander to drain excess water. Transfer to a 9 x 13-inch baking dish. Pour the sauce, tuna, and vegetables over the noodles and use tongs to coat.

  9. In a small bowl, use a fork to mash together the remaining 1/3 cup of Parmesan, pork rinds, and remaining tablespoon of olive oil. Crumble the mixture over the casserole.

  10. Bake for 10 to 15 minutes, until bubbly. Broil for 2 to 4 minutes, until the topping is golden brown.

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