This low carb take on the classic Tuna Casserole from your childhood is so tasty you won't even miss the pasta. Tuna, peas, and cauliflower smothered in a cheesy sauce baked to perfection with a crispy topping is the comfort food we all need!
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Tuna casserole was one of my favorite childhood meals and it's something that I still make all the time for my kids.
Traditionally Tuna Casserole is loaded with pasta, but to make it a little healthier I decided to try subbing the pasta for cauliflower and it was honestly just as good. Even my kids loved it and didn't mind the cauliflower at all!
Tuna casserole is also pretty versatile. You can easily change up many of the ingredients to suit your taste so be sure to check out the substitutions below!
Ingredients and substitutions:
Cauliflower - I used fresh cauliflower, but frozen cauliflower would also work. If cauliflower isn't your thing you can sub any cooked pasta that you like. My favorite is Great Low Carb Bread Co Macaroni!
Butter or butter substitute
Mushrooms - I like to use baby Bellas because they have a mild flavor. I don't really love mushrooms, but they add SO much flavor to this dish that I don't recommend leaving them out. Instead, I just chop them really small.
Unsweetened Almond Milk - Sub with traditional milk or any milk substitute that you like.
Cheddar Cheese - Cheddar is the classic choice, but you can play around with other cheeses if you like.
Salt and Pepper
Canned Tuna - you can swap with canned chicken if you aren't a fan of tuna.
Frozen Peas - I know many people eating a keto diet avoid peas, these only add a few grams of carbs per serving, but if you are opposed you can leave them out.
Keto Butter Crackers - If you haven't tried my recipe for keto butter crackers yet, do it STAT! They are my most popular recipe and for good reason! They have a similar texture and taste to club crackers and make the perfect topping for this casserole. But don't worry, if you don't want to make them, I have included an alternate topping in the notes section of the recipe card.
Tips for making the perfect low carb tuna casserole:
- Be sure not to overcook the cauliflower in the first step. It will continue to cook when you bake the casserole so if you oversteam it, it will turn to mush. You want it just barely fork tender.
- As I mentioned above, if you aren't a fan of mushrooms I recommend chopping them into very small pieces. They add a great flavor, and when they are chopped really small you won't notice them much.
- Unfortunately, I've not had good luck with freezing this recipe. You can, however, prepare the dish a few hours in advance and store it in the fridge until you are ready to bake it.
- Leftovers will keep in the fridge for about 5 days and can be reheated in the microwave, oven, or air fryer.
If you like this, then be sure to check out these other great low carb casseroles:
- Poppyseed Chicken Casserole
- Loaded Cauliflower Casserole with Chicken
- Upside Down Bacon Cheeseburger Casserole
- Chicken, Broccoli, and Cauliflower Rice Casserole
- Upside Down Pizza Casserole
- Chicken Parmesan Casserole
- Chicken Pot Pie
- Cheesy Spaghetti Squash Casserole with Pork Chops
- Kentucky Hot Brown Casserole
- 1 Medium Head of Cauliflower cut into bitesize florets
- 1 tablespoon Butter
- ½ cup Mushrooms diced
- 1 cup Unsweetened Almond Milk
- ¼ cup Heavy Cream
- 2 oz Cream Cheese
- 2 cups Cheddar Cheese Shredded, divided
- Salt and Pepper
- 16 oz Tuna Canned in water, drained
- 1 cup Frozen Peas
- 1 serving Keto Butter Crackers optional, crumbled (see alterative in notes)
- Preheat the oven to 350 degrees F and grease a 9x13” pan with nonstick spray or oil.
- Steam the cauliflower just until it is tender, being careful not to overcook it.
- While the cauliflower is steaming, Heat a medium skillet over medium-high heat. Melt the butter in the skillet, add the mushrooms and saute until the mushrooms are tender (3-4 minutes).
- Add the almond milk, heavy cream, cream cheese, and salt and pepper to taste. Cook, stirring frequently until cream cheese is melted.
- Stir in 1 ½ cups of the cheddar cheese until melted. Remove from heat and set aside.
- When the cauliflower is done steaming, thouroughly drain the water. In a large bowl, combine the cauliflower, peas, tuna, and cheese/mushroom sauce. Stir well then transfer to the prepared baking dish.
- Top with the remaining ½ cup of cheddar cheese, and the crumbled crackers.
- Bake for 30 minutes or until the cheese is melted and slightly brown.
Be sure to read the entire post for tips, tricks, and help troubleshooting.
The nutrition information listed here is only an estimate and is simply provided as a courtesy. It nor any other information within this post should constitute medical or nutritional advice. Be sure to read all packaging and ingredient labels for potential allergens. Optional ingredients are not included unless otherwise specified.