Keto tuna casserole

Just like mom used to make—NOT. Ditch the noodles in favor of celery, onions, and peppers, and indulge in a keto meal that's ready in 30 minutes. It's a whole new, delicious thing.
Just like mom used to make—NOT. Ditch the noodles in favor of celery, onions, and peppers, and indulge in a keto meal that's ready in 30 minutes. It's a whole new, delicious thing.


4 servingservings
  • 2 oz. 50 g butter
  • 1 1 yellow onionyellow onions
  • 1 1 green bell peppergreen bell peppers
  • 513 oz. 150 g celery stalkcelery stalks
  • 1 lb 450 g tuna in olive oil, drained
  • 1 cup 225 ml mayonnaise
  • 4 oz. 110 g freshly shredded parmesan cheese
  • 1 teaspoon 1 teaspoon chili flakes
  • salt and pepper
  • 6 oz. 175 g baby spinach
  • 4 tablespoons 4 tablespoons olive oil


Instructions are for 4 servings. Please modify as needed.

  1. Preheat the oven to 400°F (200°C). Chop onion, bell pepper and celery finely and fry in butter in a large frying pan until slightly soft. Season with salt and pepper.
  2. Mix tuna, mayonnaise, parmesan cheese and chili flakes in a greased baking dish. Add fried vegetables and stir.
  3. Bake for 15-20 minutes or until golden brown.
  4. Serve with baby spinach and olive oil.


Canned tuna is a life-saver when fridge and freezer are empty. Try to choose high-quality, MSC-labeled tunafish—preferably in olive oil instead of sunflower oil.

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  1. Chad
    Very filling and the tuna was a welcome change from all the yard-bird I've been eating lately. This was very quick and supper simple to fix. I did omit the green bell pepper and chili flakes I love them both but not sure I would use them with tuna. I did sprinkle the top with bacon bits and a thin layer of a fiesta cheese mix before putting it in the oven. I might add some green peas, mushrooms and pimentos next time although will bump up the carbs a bit.
  2. suzann
    Do you foodies think i could sub salmon? I'm new to sea food but I've got some salmon in the freezer.
  3. Carole
    This is pretty good, not exciting, but I'll make it again. I followed the recipe pretty closely. The parmesan gets some crunchy bits in the oven, which is great. I used tinned tuna, but you could also use tinned salmon.
  4. Maha
    I made this last night, and holy tuna casserole, was this delicious! I followed the recipe nearly exactly (yellow bell pepper instead of green, less chili flakes to taste). My kids loved it too, even my pickier eater. My other son wanted to make sure there were leftovers for his lunch today. And I'm looking forward to lunch too! This is a great recipe to double or triple and freeze in portions. I think the key to this recipe is to use quality ingredients. The mayonnaise I bought is a small fortune, but it's made with normal ingredients (except the soybean oil) and tastes really good. The tuna I use is not the yucky standard that is cooked twice, but one that is cooked just once and retains all the yumminess of tuna. I think this recipe lends itself well to variations - adding mushrooms, using jalapenos, making lettuce boats/bites, topping a tomato bowl or slice and add chopped avocado, etc. An excellent recipe, thank you!
  5. Cindy
    Very good! I used chopped up broccoli stems since I didn't have a pepper on hand. Also added mushrooms and cheddar cheese on top. I'll be making this again!
  6. carol
    Just made this, with grated mozzarella and grated cheddar on top. Lovely.
  7. Unni Furseth
    One of my favorites! I'm just about to make 12 portions and freeze, so I have something delicious the days I don't have the time to cook. And you get first class mayonnaise by making it yourself, recipe on this fantastic website! Thank you for all these wonderful, tasty keto recipes!!!
  8. Ibán
    very tasty thanks!
    however mine came out with a lot of oil on the bottom of the pan, maybe because I used olive oil based mayonnaise
  9. Rads
    Hi! This looks delicious. I live in India and ovens are not staple here, just stove tops hobs. Can I make this on stove top? If yes, how long should the mix cook? Or is it better to make this in an electronic slow cooker, which I have?
  10. Rads
    And can I use fresh tuna chunks, which I just froze today!
  11. Karina
    Loved it!
  12. Brenda
    Does this really take 4 4oz cans of tuna to make the 1 pound?
  13. Phil
    Perhaps my mayo in the UK is different but the amount of oil when I took it out of the dish was incredible and swamped the plate ... I followed the recipe exactly? Any ideas? or maybe I can replace the mayo with something else?

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