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This Low Carb Tuna Casserole (With Cauliflower) is the perfect comfort food meal! It’s easy to prepare, comes together in one casserole dish, and is packed with protein, veggies and we’ve offered two versions to make it low-carb with or without gluten-free pasta. Made in partnership with my friends at Genova Seafood.

Low Carb Cauliflower Tuna Casserole (Keto)

Low Carb Tuna Casserole (With Cauliflower)

Tuna casserole is such a classic comfort food! It’s creamy, cheesy and delicious but typically loaded with pasta and processed condensed soup! No hate on that version, but we decided it was time to re-make this dish making it gluten-free and low-carb. We tested two versions, one with pasta and one without so you can choose what amount of carbs you’d like!

For the lower carb version, we use half cauliflower and half brown rice pasta. This version is a bit more kid-friendly and has more of a classic feel to it. For our low carb version we completely swapped out the pasta for cauliflower to keep all that decadent creaminess  without any of the guilt for all of those on a low carb diet (oh hey keto diet). Either way, with whatever version you choose, you’re going to be satisfied after eating this tuna noodle casserole!


Of course we made this in partnernship with my friends at Genova Seafood. They are my favorite, trusted tuna company. Genova sources 100% of their tuna from fisheries that are MSC certified, meaning their tuna is sustainably sourced! It honestly is the best premium tuna in the purest olive oil. It is my favorite tasting tuna out there! Always non-GMO, wild-caught, and has 14g of protein in every serving!

MSC certified products must meet rigorous standards for sustainable fishing practices, like limiting by-catch (unwanted fish), avoiding overfishing and protecting marine environments. Today, only 12% of global wild caught seafood is MSC certified, and Genova Seafood is one of the companies working hard to make a change!

keto tuna cauliflower casserole

How do you make homemade tuna noodle casserole?

It’s simple:

  1. If you’re making the pasta version you boil the pasta until al dente.
  2. Saute your aromatics. Here we are using onion, celery and garlic.
  3. Make your base cheese-y sauce (also called a béchamel), using gluten-free ingredients, of course.
  4. Add in the cauliflower and cooked pasta (if using) and bake! We love using an oven safe pan to both start the casserole on the stove and then finish in the oven.

Cooking tools we used with this recipe:

  • Heavy Bottom Pan (We use one that doubles as an oven safe dish to keep the clean-up minimal)
  • Whisk
  • Spatula

tuna cauliflower casserole recipes

Want other tuna recipes? Try these favorites:

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Low Carb Tuna Casserole (With Cauliflower)

4.75 from 8 votes
Servings 4 -6
Prep Time 10 minutes
Cook Time 30 minutes
Total Time 40 minutes


  • 2 tablespoons butter
  • 1 onion diced
  • 2 celery stalks diced
  • 3 cloves garlic
  • 3 tablespoon arrowroot
  • 2-1/2 cups cashew milk or milk of choice
  • 1 tablespoon dijon mustard
  • 1 teaspoon ground black pepper
  • 1 teaspoon fine sea salt
  • 1/2 teaspoon paprika
  • pinch cayenne optional
  • 1/2 cauliflower about 1 lb., cut into florets (For Low Carb Version use 1 whole cauliflower, about 2-2-1/2 pounds and slice into pieces about 1/4" thick)
  • 2-4 oz cans genova tuna drained
  • 6 ounces brown rice pasta cooked al dente (For Low Carb Version Omit This)
  • 1/3 cup frozen green peas optional
  • 3/4 cup shredded sharp cheddar cheese divided
  • scallion for garnish


  • Pre-heat oven to 400ºF.
  • Heat a large heavy bottom pan, over medium heat and melt butter. Add onion and celery cook until beginning to soften, about 5-7 minutes.
  • Add garlic, and cook for 30 seconds.
  • Sprinkle in arrowroot, and then slowly whisk in cashew milk (or milk of choice) a 1/2 cup at a time to avoid any lumps. (see note)
  • Add dijon mustard, salt, pepper, paprika and cayenne, if using, and whisk to combine.
  • Add cauliflower and simmer for 5 minutes, stirring occasionally.
  • Remove from heat and stir in 1/2 cup of cheese. Then add in Genova Seafood Tuna, al dente cooked pasta (Omit for Low Carb Version), frozen peas and mix to fully combine.
  • Pour into an oven safe dish (if not using one already) and top with remaining 1/4 cup cheese and bake until cauliflower is tender and cheese is melted, 15-20 minutes. If you want the cheese to be bubbly and slightly browned, place under the broiler for 3-5 minutes.
  • Top with scallions and let sit for 5 minutes before serving.


The sauce may seem really thick before it goes in to the oven, but the cauliflower and the tuna exude a lot of liquid so the extra thick sauce stops it from becoming to0 watery after it is baked.


Calories: 208kcalCarbohydrates: 9.7gProtein: 20gFat: 10.1gSaturated Fat: 5.6gCholesterol: 42mgSodium: 551mgFiber: 2.3gSugar: 4.5g
Author: Lexi

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Recipe Rating


  1. 5 stars
    I made this with all cauliflower for low carb. I had the frozen riced cauliflower you get at the store. I just microwaved it enough to thaw it out. It worked really good. I substituted corn starch for the arrowroot , i used skim milk and I used brown mustard for dijon. I also only had shredded mozzarella in the fridge. It all turned out good. I really liked it and have added it to my list of healthy recipes.

  2. Hi , if i make this low carb , without pasta , what else can i serve this as a side dish ? A Salad or Toasted Bread will be good ?

  3. 5 stars
    Lexi, thanks for getting back with me! Made your recipe last night. Used cauliflower, cornstarch, and sharp cheddar cheese. Was satisfying! Liked the low carb version. Will make again! Your recipes A.L.L. taste good!

  4. I have everything to make this recipe EXCEPT arrowroot powder.

    Does anyone know how much Xanthan Gum I need to use in this recipe. Thanks for your help.

    1. Hi Donna! Personally, I do not believe xantham gum will work for this. Another option that we do know will work is tapioca starch or cornstarch. If you do experiment with xantham gum, let us know how it works!

  5. 4 stars
    Such a great way to use pantry staples. My husband even said, “this is a great way to use the cauliflower.” We both loved it!

  6. Yes, you can use xanthem gum. I did and it came out awesome (and lower carb). I also used heavy cream and 1/2 cup of chicken broth. After adding the cheese to the sauce over low light and whisking I added the anthem gum. Thick and creamy. Absolutely delicious. I also added sautéed mushrooms.

  7. 5 stars
    This recipe was excellent! I made it for supper tonight. I forgot the frozen peas, though. So I guess, I might have to make it again!

  8. Good stuff right here! Made this for dinner tonight. I added mushrooms and extra peas and I put some pork rind dust on top. So good and no unhappy tummy! Thank you!

  9. Love how you’re completely transformed traditional tuna noodle casserole using no condensed soups, fresh ingredients, and lots of veggies!! 🙂

  10. 5 stars
    This tuna casserole looks amazing! I just need to go do a market run so I can get the right ingredients to make it. thanks!

  11. I agree with Gaby’s comment, “what can’t cauliflower do?” ha! You make this look delectable, I’m bookmarking now! I’ve never used tuna in oil, would tuna in water dry this out too much? I’m trying to keep to high protein but also, lower calorie…I have you tried it this way?
    just got a great new resource for more low carb recipes, Melanie Wildman’s, The Ultimate Protein Cookbook. I love it. You might like it too!
    Thanks for this recipe Lexi!

    1. Hi Julie! Kelli here, I’m part of the LCK team. We updated to include our favorite cheese with this recipe: sharp cheddar! Enjoy!

  12. I LOVED tuna noodle casserole as a kid and it’s been so long since I’ve had it! This is a great reminder that it’s entirely possible to make a cleaner GF version. I want to dive right into that casserole dish!

  13. 5 stars
    Exceptional recipe and photography! Great job Lexi! One small question: can we use cornstarch in place of arrowroot? We live in Greece, and it’s a bit difficult to get it here:)
    Greetings from Athens!
    Mirella and Panos