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Cheesy Low-Carb Tuna Casserole

★★★★★★★★★★
4.6 stars, average of 196 ratings

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Comfort food for my partner is anything hot and cheesy, but eating too much of it can feel heavy. This keto casserole strikes the perfect balance, combining a creamy, cheesy sauce with low-carb vegetables and canned tuna. It’s hearty without being overly rich, making it a go-to dinner for us.

This recipe makes 4 regular servings or 2 to 3 larger portions, especially if you follow a higher-protein keto diet. Enjoy!

Why This Recipe Is Perfect for Keto

  • Perfect for Meal Prep: It’s freezer-friendly and stays fresh in the fridge for up to five days.
  • Ideal for Busy Weeknights: Minimal prep and just 20 minutes of cooking time. Naturally Low-Carb and High in Protein: Great for keto diets or anyone looking to cut carbs.
  • Budget-Friendly: Uses affordable pantry staples like canned tuna and simple veggies.
  • Quick and Easy: Made with common ingredients you probably already have on hand.

Key Ingredients & Swaps

Here’s a breakdown of the key ingredients for this casserole, along with some easy swaps to suit your preferences:

  • Broccoli and Cauliflower: These are great low-carb options, but you can easily swap them for zucchini, spinach, green beans, or even bell peppers. Frozen veggies work just as well—just thaw and drain them before using.
  • Canned Tuna: A budget-friendly and high-protein choice. If you prefer other options, try canned or smoked salmon, mackerel, or sardines. Not a fan of fish? Use shredded rotisserie chicken or leftover cooked turkey instead.
  • Keto Cheese Sauce: The star of the dish, this creamy sauce ties everything together. You can stick with the classic Keto Cheese Sauce, or try other options like Herb Cheese Sauce for a fresh, herby twist, or Blue Cheese Sauce for a bolder flavor.
  • Grated Cheese: Mozzarella or cheddar works well for that melty top layer, but feel free to experiment with other types like gouda or Monterey Jack.

Cheesy Low-Carb Tuna CasserolePin itFollow us 148.4k

Tips for Making the Perfect Cheesy Tuna Casserole

To make sure your cheesy low-carb tuna casserole turns out just right, keep these tips in mind:

  • Don’t Overcook the Veggies: Steam the broccoli and cauliflower until just tender to avoid them getting mushy in the oven.
  • Drain the Tuna Well: Excess liquid can make the casserole watery, so be sure to drain the canned tuna thoroughly.
  • Mix the Ingredients Gently: When combining the cheese sauce with the veggies and tuna, gently fold them together to keep the veggies from breaking apart.
  • Use an Ovenproof Dish: Pick a dish that can go from prep to baking and is large enough to hold all the ingredients comfortably.
  • Check for Bubbling Cheese: The casserole is done when the cheese is golden and bubbling on top, which usually takes around 15 minutes.

Storage Tips

To store leftovers, let the casserole cool completely before transferring it to an airtight container. It will stay fresh in the fridge for up to five days. If you want to freeze it, you can do so in individual portions or as a whole in a freezer-safe container for up to three months. Just remember to thaw it in the fridge overnight before reheating.

When it’s time to reheat, the best way is to pop it in the oven at 350°F (175°C) for about 10-15 minutes until heated through. This helps maintain the crispy cheese topping. If you’re in a hurry, you can microwave individual portions, but you may lose some of that nice, cheesy texture.

Similar Recipes You'll Love

Love low-carb casseroles? Check out some of these recipes:

Cheesy Low-Carb Tuna Casserole Cheesy Low-Carb Tuna Casserole Cheesy Low-Carb Tuna Casserole
Cheesy Low-Carb Tuna Casserole Cheesy Low-Carb Tuna Casserole Cheesy Low-Carb Tuna Casserole

Hands-on Overall

Serving size about 255 g/ 9 oz

Allergy information for Cheesy Low-Carb Tuna Casserole

✔  Gluten free
✔  Egg free
✔  Nut free
✔  Nightshade free
✔  Pork free
✔  Avocado free
✔  Coconut free
✔  Shellfish free
✔  Beef free
Pescatarian

Nutritional values (per about 255 g/ 9 oz)

Net carbs5.8 grams
Protein29.6 grams
Fat22.6 grams
Calories342 kcal
Calories from carbs 7%, protein 34%, fat 59%
Total carbs8.1 gramsFiber2.3 gramsSugars3 gramsSaturated fat13.3 gramsSodium528 mg(23% RDA)Magnesium50 mg(13% RDA)Potassium550 mg(27% EMR)

Ingredients (makes 4 servings)

  • 1/2 head broccoli (200 g/ 7.1 oz)
  • 1/2 head small cauliflower (200 g/ 7.1 oz)
  • 1 large can of tuna, drained (375 g/ 13.2 oz)
  • 1 recipe Keto Cheese Sauce (makes about 1 cup/ 240 ml)
  • 3/4 grated mozzarella cheese or cheddar (85 g/ 3 oz)

Instructions

  1. Preheat oven to 180 °C/ 355 °F (conventional), or 160 °C/ 320 °F (fan assisted).
  2. Chop the broccoli and cauliflower into small florets and steam until just tender. Set aside to cool slightly. If you're using frozen and thawed vegetables, you won't have to cook them. Cheesy Low-Carb Tuna Casserole
  3. Add the vegetables and tuna to a large ovenproof dish and pour over the sauce, then gently stir through.
    Cheesy Low-Carb Tuna Casserole
  4. Sprinkle with the cheese.
    Cheesy Low-Carb Tuna Casserole
  5. Bake 15 minutes or until golden on top.
    Cheesy Low-Carb Tuna Casserole
  6. Serve or let it cool down and store in the fridge up to 5 days. Reheat before serving.
    Cheesy Low-Carb Tuna Casserole

Cheesy Tuna Casserole
Step by Step

★★★★★★★★★★
4.6 stars, average of 196 ratings
Cheesy Tuna Casserole
Easy high-protein keto dinner casserole made with just 5 ingredients! Juicy tuna and low-carb veggies covered in creamy homemade cheese sauce and baked with melty cheese.
Hands on10m
Overall25m
Servings4
Calories342 kcal
Pin it

Ingredients

  • 1/2 head broccoli (200 g/ 7.1 oz)
  • 1/2 head small cauliflower (200 g/ 7.1 oz)
  • 1 large can of tuna, drained (375 g/ 13.2 oz)
  • 1 recipe Keto Cheese Sauce (makes about 1 cup/ 240 ml)
  • 3/4 grated mozzarella cheese or cheddar (85 g/ 3 oz)

Instructions

  1. Preheat oven to 180 °C/ 355 °F (conventional), or 160 °C/ 320 °F (fan assisted).
  2. Chop the broccoli and cauliflower into small florets and steam until just tender. Set aside to cool slightly. If you're using frozen and thawed vegetables, you won't have to cook them.
  3. Add the vegetables and tuna to a large ovenproof dish and pour over the sauce, then gently stir through.
  4. Sprinkle with the cheese.
  5. Bake 15 minutes or until golden on top.
  6. Serve or let it cool down and store in the fridge up to 5 days. Reheat before serving.

Nutrition (per serving, about 255 g/ 9 oz)

Calories342kcal
Net Carbs5.8g
Carbohydrates8.1g
Protein29.6g
Fat22.6g
Saturated Fat13.3g
Fiber2.3g
Sugar3g
Sodium528mg
Magnesium50mg
Potassium550mg

Detailed nutritional breakdown (per about 255 g/ 9 oz)

Net carbsProteinFatCalories
Total per about 255 g/ 9 oz
5.8 g29.6 g22.6 g342 kcal
Broccoli, broccolini, fresh
2 g1.4 g0.2 g17 kcal
Cauliflower, fresh
1.5 g1 g0.1 g13 kcal
Tuna, tinned (in brine), drained
0 g18.2 g0.9 g81 kcal
Keto Cheese Sauce, homemade, basic (KetoDiet blog)
1.1 g4 g17.2 g169 kcal
Mozzarella cheese (low moisture, for pizza)
1.2 g5 g4.2 g63 kcal

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Dearna Bond
Creator of ToHerCore.com

Dearna Bond

Dearna is a passionate foodie and food photographer, and loves sharing her knowledge and enthusiasm for both via her food blog and online photography courses.

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Comments (7)

Love this recipe. Thank you for sharing.

I have the app but the cheesy low carb tuna casserole recipe on the blog I cannot add to my planner!!!!

Hi Pat, I'm sorry if there was a glitch - I seem to remember I fixed this (I always have to add a special code for that and I think I may have forgotten). It seems ok now, is it ok for you too? Just checking. Thank you!

Hi, I have just tried but still no add available at top right.
Take care, go well,
Pat Holland

I'm sorry about that Pat, I just checked and it works on two of my devices. Could you please send me a screenshot on Facebook (via DM) or at martina[at]ketodietapp[dot]com? Thank you!

Hello. I really want to make this. My younger sister bought me a 600ml double cream for the cheese sauce. This recipe only calls for 60mls. What do I do with the remaining cream? Especially as the cream has a very short shelf life. Would the cream last longer if I freeze it?
I've been going through this app for quick recipes that use double cream and I found chocolate truffles. But there'll still be loads of cream left!!

Hello Amina, you can freeze cream in an ice tray or in a freezer-friendly container.
Or you could make keto coffee creamer and condensed milk: Low-Carb & Keto Coffee Creamer Five Ways, or ice cream: Ice Creams
Truffles are an option too 😊