This delicious and filling low carb and keto tuna casserole has no noodles, but it does have lots of flavor! Plus it’s so easy to make.
Canned tuna is one of my favorite ingredients. It’s tasty, filling, and very affordable. I use it to make tuna cakes, tuna salad, and keto tuna melt.
This low carb keto tuna casserole is so good! It has no noodles, and I promise – 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.
The ingredients you’ll need
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 because it’s lower in mercury than other tuna species.
Mayonnaise: I like using avocado oil mayonnaise.
Dijon mustard: It’s creamier and less vinegary than yellow mustard.
Shredded Gruyere cheese: Other melty cheeses such as cheddar or provolone work too.
Chopped red onion: Make sure it’s finely chopped. I’m lazy so I chop it in the food processor.
To season: Salt, black pepper, and cayenne pepper.
Chopped parsley: Used mostly for garnish, so you can skip it if you don’t have it on hand.
How to make keto tuna casserole
It’s so easy! Scroll down to the recipe card for the detailed instructions. Here are the basic steps:
1. Simply mix everything together, reserving part of the cheese and the parsley.
2. Then transfer the mixture to a small baking dish and sprinkle with cheese.
3. Bake for 15 minutes at 400°F, garnish with parsley and serve.
Bulk it up with riced cauliflower
You can bulk up this casserole by adding 2 cups of cooked riced cauliflower, increasing the mayonnaise to 1/2 cup, and dividing it into 3 servings. But I usually don’t, because my husband and I like the casserole better without cauliflower.
What to serve with keto tuna casserole
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’s also good with a side of microwave broccoli.
What to do with leftovers?
Leftovers keep well in the fridge for 3-4 days, or you can freeze them if you want to keep them for longer. Gently reheat them in a 300°F oven, or in the microwave on 50% power.
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Keto Tuna Casserole
INGREDIENTS
- 2 (5oz) cans tuna in water, drained
- 1/3 cup avocado oil mayonnaise
- 1 tablespoon Dijon mustard
- 1/2 cup shredded gruyere, divided
- 1/4 cup chopped red onion
- 1/4 teaspoon sea salt
- 1/4 teaspoon black pepper
- ¼ teaspoon cayenne pepper
- ¼ cup chopped parsley for garnish
INSTRUCTIONS
- Preheat oven to 400 degrees F.
- Mix together the tuna, mayonnaise, mustard, 1/4 cup cheese, onion, salt, pepper and cayenne.
- Transfer the mixture to a small, 1-quart casserole dish. Sprinkle 1/4 cup shredded cheese on top.
- Bake until hot, about 15 minutes. Sprinkle with parsley and serve immediately, with cut-up veggies.
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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, Reader's Digest, and Better Homes and Gardens.