Home » Keto Casseroles » Keto Tuna Casserole
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This delicious and filling keto tuna casserole has no noodles, but it has plenty of flavor!
Ready in just 30 minutes and using simple everyday ingredients, this easy recipe is perfect for a weeknight dinner.
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.
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- Ingredients
- Variations
- Instructions
- Expert Tip
- Recipe FAQs
- Reader Review
- Serving Suggestions
- Storing Leftovers
- More Seafood Recipes
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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.
- 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.
Variations
- You can use tuna in olive oil instead of tuna in water. It's delicious!
- Try using sour cream instead of mayonnaise. Both work, but personally, I prefer mayonnaise.
- Dill makes a nice addition to this recipe.
- Sharp cheddar or provolone are good substitutes for Gruyere. Smoked Gouda is also very good.
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. (Photos 1-2).
- Next, transfer the mixture to a small baking dish and sprinkle the top with the remaining cheese. (Photo 3).
- Bake the casserole until heated through, about 15 minutes in a 400°F oven. Garnish with parsley and serve. (Photos 4-6).
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.
Recipe FAQs
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, keto 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.
Reader 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 to it. This was amazing with the sautéed 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
The 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 at 50% power.
More Seafood Recipes
- Keto Tuna Salad
- Tuna Patties
- Crab Salad
- Seared Tuna
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Recipe Card
4.98 from 1159 votes
Print Recipe
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 minutes mins
Cook Time15 minutes mins
Total Time30 minutes mins
Course: Main Course
Cuisine: American
Servings: 2 servings
Calories: 465kcal
Author: Vered DeLeeuw
Ingredients
- 2 (5 oz) cans tuna in water drained
- ⅓ cup avocado oil mayonnaise
- 1 tablespoon Dijon mustard
- ½ cup Gruyere cheese shredded, divided
- ¼ cup red onion minced
- ¼ teaspoon sea salt
- ¼ teaspoon black pepper
- ¼ teaspoon cayenne pepper
- ¼ cup parsley chopped, for garnish
Instructions
Preheat your oven to 400°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, for about 15 minutes.
Sprinkle with parsley and serve immediately, with cut-up veggies and/or pork rinds for scooping out.
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.
The 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 at 50% power.
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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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Disclaimers
Cup measurements refer to the standard American cup, which is 240 milliliters. Most of my 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 these Terms of Use carefully before using any of my recipes.
More Keto Casserole Recipes
- Mushroom Casserole
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About the Author
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.
Reader Interactions
Comments
Beth
Hi, great recipe, wondering how many servings it is? Thanks. Looking forward to trying more recipes.Reply
Vered DeLeeuw
Hi Beth,
This recipe makes two servings.Reply
Lynn Maison
I made this! But, made the following adjustments...
Sprayed a 13x9 glass casserole dish
Spread a thin crust pizza dough in the dish. Spryed with butter spray and sprinkled with garlic powder and dill.
I covered with plastic wrap and set in fridge for (@ least) 30m.
Once ready, bake for 6-8m @ 400°.
While baking the crust to a lightly golden brown:
Add to a mixing bowl...
Tuna
1/4c Mayo (avocado oil, olive oil preferred)
2 tbsp Dried diced onion instead of fresh cut (all I had)
1/8c milk
1/4c sour cream
1/3c shredded cheese
Mix ingredients.Spread on top of crust. Top with the remaining cheese. Pads of butter and parmesan can be added to the top to brown.
Sprinkle with parsley or fresh diced green onions.Reply
Vered DeLeeuw
Thanks for sharing your version of this recipe, Lynn. 🙂
Reply
Winnie Haney
Made this for my husband who's on Keto. I try his stuff once in a while and love eating this myself with pig skins as a dip. I didn't have all the ingredients so tweaked a few things with the same amount of carbs, a little more cost friendly.Reply
Vered DeLeeuw
Glad you liked it, Winnie!
Reply
Jesse
This was very good. I added riced cauliflower and green peas and used white albacore tuna, it tastes less fishy to me. I also added shredded colby jack cheese because that's what I had on hand, and French fried onions on top. Thanks for sharing. I was wondering how I was going to use all the canned tuna I bought, now I know.Reply
Vered DeLeeuw
So glad you enjoyed this casserole, Jesse!
Reply
