Keto Tuna Casserole

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This Keto Tuna Casserole has all of the classic flavors of a traditional tuna noodle casserole recipe, while being low carb and gluten free. Rich and flavorful cream sauce, with onion, garlic, peas, celery, herbaceous dill, and bright, fresh lemon, paired with shredded cabbage and albacore tuna, then topped with cheese and baked until it is golden brown and bubbly. It's the perfect quick and easy weeknight meal.

a skillet full of low carb tuna casserole, rich and creamy sauce, baked golden brown with cheese

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Ingredients Notes

Ingredients for cabbage noodle tuna casserole - cabbage, tuna, lemon, garlic, cream, cheese, dill, celery

Cabbage: this is what makes this recipe a keto recipe. By using cabbage in place of traditional noodles, you can cut the carbs and the gluten. I've done this in a few other cabbage noodle recipes, like my Cheesy Smoked Sausage and Cabbage Casserole, Fried Cabbage with Kielbasa, and Egg Roll in a Bowl. I use green cabbage, but any can be used: Savoy cabbage, red cabbage, Napa cabbage, even Brussels sprouts! Cut your favorite cabbage into shreds with a knife or mandolin. You can also use coleslaw mix and make this Keto Tuna Casserole even more simple.
Tuna: for the best taste, I highly recommend using sustainably pole caught albacore, canned in water. You can also use fresh tuna or even canned or fresh salmon. For more tuna recipes, check out these Asian Tuna Cakes and Avocado Tuna Salad.
Lemon juice and zest: again, fresh is best. The lemon in this recipe really compliments the tuna and adds some bright freshness.
Dill: fresh herbs are my favorite way to add flavor to any dish. Dill is the perfect compliment to seafood, and tuna is no exception.
Peas: if you really want to cut down on carbs, you can omit the peas from this recipe entirely, but I recommend keeping them! Fresh peas add a beautiful pop of color and sweetness. You can also used canned peas.

Step by Step Instructions

STEP 1: First, heat the olive oil and butter in an extra large ovenproof skillet over medium heat.

STEP 2: Next, add the cabbage, onion, celery, garlic, sea salt and black pepper to the pan. Sauté vegetables until they are crisp tender - about 10 minutes.

STEP 3: In a separate bowl, mix in the dill, mustard powder, lemon zest, and lemon juice.

STEP 4: Add the lemon mixture to the pan. Stir to combine.

STEP 5: Pour the heavy cream and 1 cup Parmesan cheese into the pan. Mix in and keep stirring until the cheese has melted and combined with the heavy cream.

STEP 6: Then, reduce heat to medium low. Simmer, allowing the sauce to thicken.

STEP 7: Once the sauce has started to thicken, stir in the tuna and the peas.

STEP 8: Sprinkle the remaining Parmesan over the top of the dish and transfer to the oven. Lastly, broil on high for 3 to 5 minutes or until the Parmesan on top has made a golden brown crust.

Recipe Tips and Variations

Serving suggestions: I recommend serving this Keto Tuna Casserole with some of my favorite vegetable side dishes: Lemon Pepper Green Beans, Brussels Sprouts with Creamy Dijon Cider Dressing, Balsamic Shallot Mushrooms, or even a simple side salad. You can also add mushrooms to the recipe for a boost of extra veggies.
Storage: store in the fridge in an airtight container up to 3 days. If you plan to store it in the freezer, you can do so before baking for up to 3 months.
Reheating: for best results, reheat this low carb tuna casserole on the stove top or in the microwave. You can add a little cream as well to keep it from drying out, especially if reheating in the microwave.
Low carb noodle substitutions: these are plenty of low carb pasta substitutions: zucchini noodles, Shirataki noodles, rainbow vegetable noodles, and even spaghetti squash would work great in this recipe.
Protein options: not a fan of tuna? No problem. Try this tuna noodle casserole recipe with fresh chicken, canned chicken, salmon, or shrimp as an alternative protein.
Shortcuts: to make this tuna casserole dish even faster, you can use a canned cream of mushroom soup for the sauce and coleslaw mix instead of shredded cabbage. However, using canned soup will increase the carbs quite a bit.
Crispy fried onion topping: this adds a great textural contrast. I outline how to make a low carb version of crispy fried onions in this recipe.
Cheese it up: add sharp cheddar to really drive up the cheesy goodness of this recipe.
Breadcrumb topping: add a layer of crunch without the carbs or the gluten. Try topping this Keto Tuna Casserole with grated parmesan or my nut free breading mix.

Frequently Asked Questions

How do you make tuna casserole from scratch?

Cook the veggies and aromatics in olive oil and butter until just tender, mix in the seasonings, add heavy cream and Parmesan for a creamy element, and let it all thicken. Finally, add the tuna and peas, sprinkle extra Parmesan on the casserole, and bake until it reaches golden, bubbly perfection.

How many carbs does tuna casserole have?

Classic homemade tuna noodle casserole uses pasta as the basis, and a small serving will have at least 22g of carbs. This is a Keto Tuna Casserole, so there are only 7g net carbs per serving.

What's the best low carb pasta?

Some great options for low carb pasta are Shirataki noodles, spaghetti squash, zucchini noodles, or even cauliflower.