This Low Carb Keto Tuna Casserole is made delicious with tender cauliflower, fresh zucchini, a creamy herb sauce, chunky tuna, and layered with ooey gooey melted cheese. Sure to become a new family favorite! This healthy casserole is gluten free, sugar free, and the perfect keto dinner idea! It can also be made low fat and lighter with easy substitutions.
🎥 Recipe Video
A tasty low carb easy cheesy tuna casserole that's SO delicious! It's family-friendly, and with the vegetables it's really a healthy one-dish meal. -Kori
Why You'll ❤️ This Keto Tuna Casserole
Using canned tuna makes for a very cost-effective meal! Also, because it is a pantry staple, it has a long shelf life and doesn't take up precious space in your fridge or freezer.
The combination of tuna, dill, sauce, zucchini and cheese make this a very delicious keto tuna casserole. The zucchini and cauliflower give it a fresh taste that balances the melted cheese and tuna.
You'll love this healthy tuna casserole!
It's gluten-free, low carb, keto, and has no added sugar.
If not following keto, lower the fat by using a low-fat or fat-free sour cream and mayonnaise. Reduce the cheese to 1 cup.
It's a great way to sneak in extra veggies! Between the cauliflower and zucchini, you have a full serving of vegetables in this recipe!
With 25.5 grams of fat, and 3.4g net carbs and 20.8g protein, it fits nicely in with a low carb and ketogenic diet.
🥘 What You'll Need
Here are the ingredients that you will need to make this low carb tuna casserole:
Cooked Cauliflower - microwave, steamed, boiled, or roasted cauliflower (oven or air fryer) all work perfectly.
Canned Tuna - you can also use shrimp, crab, or salmon.
Green Onions - finely chopped shallots or red onion can be used in place of green onion.
Mayonnaise - use any favorite brand. It's fine to use a lower-fat variety if needed.
Sour Cream - same as the mayo, use a lower fat if needed.
Fresh Dill - chives, basil, parsley, and thyme can also be used.
Kosher Salt - add according to the recipe and adjust after serving.
Ground Black Pepper
Shredded Jack or Cheddar Cheese - mozzarella, swiss, or gouda will work fine too.
Crushed Pork Rinds - you can crush your own pork rinds or buy them already crushed.
🔪 How To Make It
Here are the step-by-step instructions for making low carb tuna casserole:
Okay, this is so easy and good you will wonder why you have never made this before! 🙂 Here are the steps to make this super delicious keto seafood casserole:
Prep And Assemble Your Ingredients
Cook the cauliflower.
Preheat your oven to 350 degrees.
Drain the tuna and set aside.
Chop your vegetables and assemble all other ingredients.
Make Tuna Mixture
In a bowl, combine cauliflower, drained tuna, celery, green onions, mayonnaise, sour cream, mustard, herbs, salt, and pepper.
Layer Zucchini and Cheese
In a buttered 1.5-quart casserole dish, spoon half of the tuna mixture and spread evenly.
Layer with half the zucchini and then half the cheese.
Top with the remaining half of the tuna mixture, zucchini, and finish by topping with cheese.
Sprinkle top with pork rind panko.
Bake for 40 minutes or until the dish is hot and the cheese is bubbly.
Let the casserole sit for about 5-10 minutes before serving.
🥗 How To Serve It
Here are a few ways to serve this low carb keto tuna casserole:
Garnish with fresh herbs.
Topping it with diced tomato and sometimes avocado is a great way to sneak in extra veggies!
Top it with a dollop of sour cream or even additional shredded cheddar cheese, jack or parmesan cheese.
Meal idea! Serve your tuna casserole with a fresh green salad and this delicious Creamy Dill Dressing.
Here are a few ways you can vary or make substitutions to this keto tuna casserole recipe:
Use a salted seafood seasoning in place of the salt. Adjust seasoning to taste with salt after serving.
Slice the zucchini or make zucchini noodles. I found it faster to slice then to make the zucchini noodles.
¼ cup softened cream cheese can be added if desired.
Use a full fat, low fat, or fat free mayonnaise and sour cream - depending upon your dietary needs.
Add a little spice with some red pepper flakes or cayenne pepper.
Most canned seafood can replace the tuna - salmon, crab, and shrimp - or a combination is delicious.
Substitute broccoli for cauliflower.
💭 Top Tips
- Slice the zucchini very thin to help it cook faster in the casserole.
- Adjust any seasoning to taste.
- Use 1 teaspoon dried herbs for every 1 tablespoon.
- If the casserole is browning too fast, cover it with foil.
- Crush your own pork rinds if you can't find the panko.
- Use butter, olive oil, or cooking spray to coat the casserole dish.
How To Store
To store leftovers, let the casserole cool completely, then transfer to an airtight container. Store in the refrigerator for up to 4 days. See reheating instructions below.
How To Reheat
Oven: preheat oven to 350 degrees. Transfer the casserole to an oven-safe dish and cover it with foil. Bake until heated through, about 20 minutes.
Microwave: in a microwave-safe dish, cook covered for 1 to 2 minutes until heated through. Adjust heating time and temperature according to your microwave wattage.
Yes! Tuna is very low in carbs and is perfect on a low-carb and keto diet. It is also sugar-free and gluten-free.
The answer to that depends on which recipe you are following and can vary widely. This tuna casserole contains 4.8 grams of cabs, 1.4 g of fiber, and only 3.4 grams of net carbs.
Yes, absolutely. Tuna has almost no carbs, sugar, and is gluten-free. Because it is lower in fat it is usually combined with healthy fats such as avocado, mayonnaise, cheese, etc.
✔️ Related Recipes
Here are several low-carb keto casserole recipes, and more ideas for cooking seafood, enjoy!
- Baked Salmon with Mayo and Parmesan Herb Crust
- Parmesan Crusted Air Fryer Tilapia
- Smoked Salmon Frittata Recipe
- Grilled Shrimp Salad Recipe
- Keto Stir Fry with Shrimp
More Keto Casserole Recipes
- Keto Chicken Pot Pie Casserole
- Creamy Chicken and Asparagus Bake (Low Carb Keto)
- EASY Jalapeño Popper Chicken Casserole (Keto Low Carb)
- Chicken Fajitas Bake
If you tried this keto tuna casserole, let me know! I'd love for you to come back and give it a 5-star rating and/or a review in the comments! 🙂 Let's stay connected, so please share photos of your creations with me and others on Instagram, Facebook, and Pinterest! Don't forget to tag #seekinggoodeats
Low Carb Keto Tuna Casserole
- 3 cups cooked cauliflower (florets about 1" to 1½" in size)
- 2 (6.5-ounce) cans drained tuna (or, salmon, crab, or shrimp)
- ½ cup chopped celery
- ½ cup sliced green onions
- ½ cup mayonnaise
- ½ cup sour cream
- 2 teaspoons dijon mustard
- 1 tablespoon fresh dill (or, 1 teaspoon dried)
- ½ teaspoon kosher salt
- ¼ teaspoon pepper
- 1 small zucchini (very thinly sliced)
- 1½ cups shredded cheddar or jack cheese (or, mozzarella, swiss, gouda)
- ¼ cup crushed pork rinds
- Preheat oven to 350 degrees. Prep and assemble your ingredients. Drain tuna (or other seafood), and set aside.
- In a bowl, combine cauliflower, tuna, celery, green onions, mayonnaise, sour cream, mustard, dill, salt, and pepper.
- In a buttered 1½-quart casserole dish, spoon half of the tuna mixture. Layer half the zucchini and half the cheese. Top with the remaining half of the tuna mixture and zucchini. Finish with cheese.
- Sprinkle crushed pork rinds over the top. Bake at 350 degrees for 40 minutes until the dish is hot and cheese is bubbly.
- Sprinkle with fresh dill and serve.
- Don't miss all of our helpful hints, substitution ideas, cooking tips, and other delicious recipes that can be found in our post. Check it out!
- VARIATIONS: Substitute canned shrimp or salmon; use chives, parsley, or thyme in place of dill - or a mix; mozzarella, jack, or cheddar cheese can be used; green onion can be added to the casserole.
- TIPS: Roasted (oven or air fryer), boiled, or steamed cauliflower will all work great. The best flavor is roasted cauliflower. Reduce the amount of salt called for when roasting.
- SERVING SUGGESTIONS: Adjust salt and pepper. Garnish with fresh dill or chives and diced tomato.
© 2023 Seeking Good Eats™