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    Home » Keto Casseroles » Keto Tuna Casserole

    Keto Tuna Casserole

    Last updated: Jul 11, 2022 · Recipes developed by Vered DeLeeuw and nutritionally reviewed by Rachel Benight MS, RD · This website generates income via ads and uses cookies.

    Jump to Recipe Card

    This delicious and filling tuna casserole has no noodles, but it has plenty of flavor!

    Ready in just 30 minutes and using simple everyday ingredients, this easy keto recipe is perfect for a weeknight dinner.

    Tuna casserole served in a white baking dish.

    Canned tuna is one of my favorite ingredients. It's tasty, filling, and very affordable. And just as important - I always have it on hand, making it the natural choice when the fridge is otherwise bare. I use it to make tuna cakes and tuna salad.

    I also use it to make this tuna casserole. It's so good! It has no noodles, but you won't miss them. It's a lazy casserole - minimal chopping necessary. And it's ready fast, so it's perfect for weeknight dinners.

    Jump to:
    • Ingredients
    • Instructions
    • Expert tip
    • Frequently asked questions
    • Variations
    • Review
    • Serving suggestions
    • Storing leftovers
    • Related recipes
    • Recipe card

    Ingredients

    This is a delicious, filling, well-seasoned mixture of canned tuna, chopped red onion, mayonnaise, and cheese, baked until golden and bubbly. Here's an overview of the ingredients - the exact measurements are listed in the recipe card below:

    Canned tuna: I use skipjack tuna in this recipe.

    Mayonnaise: I like using avocado oil mayonnaise. My favorite brand is Sir Kensington's.

    Dijon mustard: It's creamier and less vinegary than yellow mustard. I do recommend using it here rather than using yellow mustard.

    Shredded Gruyere cheese: Other melty cheeses such as cheddar or provolone should work too. But Gruyere is especially flavorful.

    Chopped red onion: Make sure it's finely chopped.

    To season: Salt, black pepper, and cayenne pepper. The cayenne pepper doesn't make the casserole very spicy, at least to my palate, but it does add a nice subtle kick.

    Chopped parsley: I use it mostly for garnish, so you can skip it if you don't have it on hand. It does add a nice splash of color, though.

    Instructions

    Making this tuna casserole is so easy! Scroll down to the recipe card for detailed instructions. Here are the basic steps:

    Simply mix all the ingredients together, reserving some of the cheese and the parsley.

    Next, transfer the mixture to a small baking dish and sprinkle the top with the remaining cheese.

    Bake the casserole until heated through, about 15 minutes in a 400°F oven. Garnish with parsley and serve.

    A photo collage showing the steps for making a tuna casserole.

    Expert tip

    You can bulk up this casserole by adding 2 cups of cooked riced cauliflower, increasing the mayonnaise to ½ cup, and dividing it into 3 servings.

    Frequently asked questions

    Why is my casserole dry?

    This casserole can become dry if the ratio of tuna to creamy ingredients (mayonnaise and mustard) is too high.

    I find that ⅓ cup of mayo works well, but depending on the brand of tuna you use, you might need to increase it and use up to ½ cup.

    Can you make a tuna casserole without noodles?

    Yes! I do it all the time. It's a different recipe than classic ones, and you'll want to serve it with something for scooping it out, such as fresh-cut veggies, crackers, or pork rinds. But it's very, very good.

    Can you freeze this casserole?

    Yes. Once completely cool, you can wrap the baking dish in plastic wrap followed by a layer of foil. Freeze it for up to three months. Thaw it in the fridge.

    Variations

    I love this recipe as is and almost always make it as written. But in case you'd like to vary the basic recipe, here are a few ideas for you:

    • You can use tuna in olive oil instead of tuna in water. It's delicious.
    • Try using sour cream instead of mayonnaise.
    • As mentioned in the review below, dill makes a nice addition to this recipe.
    • Sharp cheddar or provolone are good substitutes for gruyere. Smoked gouda is also good.

    Review

    On Instagram, @shelikeshergreens posted this gorgeous photo of her casserole. She says, "I made my own mayonnaise for this casserole. I didn’t have gruyere so I used cheddar instead. I added dill to the mix to bring some freshness into it. This was amazing with the sautéed beans!"

    A reader photo of a keto tuna casserole with a side of green beans.

    Serving suggestions

    This casserole is rich and filling. As you can see in the recipe card below, a serving has 465 calories. So I simply serve it with fresh-cut veggies for scooping it out of the baking dish (or plate). It's also good with a side of microwave broccoli.

    Storing leftovers

    Leftovers keep well in the fridge for 3-4 days, or you can freeze them for up to three months if you want to keep them for longer. Gently reheat them in a 300°F oven, or in the microwave on 50% power.

    Tuna casserole served in a white baking dish with a spoon.

    Related recipes

    • Keto Tuna Salad
      Keto Tuna Salad
    • Tuna patties.
      Tuna Cakes
    • Crab salad.
      Crab Salad
    • Tuna steak.
      Tuna Steak

    👩🏻‍🍳 I typically publish a new or an updated recipe once a week. Want these recipes in your inbox? Subscribe! You can unsubscribe at any time.

    Recipe card

    4.98 from 1118 votes
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    Keto Tuna Casserole

    This delicious and filling keto tuna casserole has no noodles, but it has lots of flavor! Plus it's so easy to make.
    Prep Time15 mins
    Cook Time15 mins
    Total Time30 mins
    Course: Main Course
    Cuisine: American
    Servings: 2 servings
    Calories: 465kcal
    Author: Vered DeLeeuw
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    INGREDIENTS

    • 2 (5 oz) cans tuna in water, drained
    • ⅓ cup avocado oil mayonnaise
    • 1 tablespoon Dijon mustard
    • ½ cup shredded gruyere cheese divided
    • ¼ cup minced red onion
    • ¼ teaspoon sea salt
    • ¼ teaspoon black pepper
    • ¼ teaspoon cayenne pepper
    • ¼ cup chopped parsley for garnish

    INSTRUCTIONS

    • Preheat your oven to 400 degrees F.
    • Mix together the tuna, mayonnaise, mustard, ¼ cup cheese, onion, salt, pepper, and cayenne.
    • Transfer the mixture to a small, 1-quart casserole dish. Sprinkle the remaining ¼ cup shredded cheese on top.
    • Bake until hot, about 15 minutes.
    • Sprinkle with parsley and serve immediately, with cut-up veggies and/or pork rinds for scooping out.

    WATCH THE VIDEO:

    NOTES

    You can bulk this casserole up by adding 2 cups of cooked riced cauliflower, increasing the mayonnaise to ½ cup, and dividing it into 3 servings. 
    Leftovers keep well in the fridge for 3-4 days, or you can freeze them for up to three months if you want to keep them for longer. Gently reheat them in a 300°F oven, or in the microwave on 50% power.

    ADD YOUR OWN NOTES

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    DISCLAIMERSMost of our recipes are low-carb (or keto) and gluten-free, but some are not. Please verify that a recipe fits your needs before using it. Recommended and linked products are not guaranteed to be gluten-free. Nutrition info is approximate and the carb count excludes non-nutritive sweeteners. Nutrition info may contain errors, so please verify it independently. Recipes may contain errors, so please use your common sense when following them. Please read our Terms of Use carefully before using any of our recipes.

    NUTRITION PER SERVING

    Serving: 0.5casserole | Calories: 465kcal | Carbohydrates: 2g | Protein: 33g | Fat: 36g | Saturated Fat: 10g | Sodium: 882mg | Sugar: 5g
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    More Keto Casserole Recipes

    • Mushroom casserole.
      Mushroom Casserole
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      Broccoli Cheese Casserole
    • Keto pizza casserole.
      Keto Pizza Casserole
    • Keto Chicken Enchilada Casserole.
      Chicken Enchilada Casserole

    About the Author

    Vered Deleeuw Vered DeLeeuw, LL.M., CNC, has been following a low-carb real-food diet and blogging about it since 2011. She's a Certified Nutrition Coach (NASM-CNC), has taken courses at the Harvard School of Public Health, and has earned a Nutrition and Healthy Living Certificate from Cornell University. Her work has appeared in several major media outlets, including Healthline, HuffPost, Today, Women's Health, Shape, and Country Living. Click to learn more about Vered.

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    Healthy Recipes Blog was founded in 2011 by Vered Deleeuw. It features real-food recipes with a focus on low-carb and gluten-free ingredients. All recipes are nutritionally reviewed by a Registered Dietitian. Contact us at HealthyRecipesBlog@gmail.com.


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