Ever had one of those days when you’re staring into the fridge, trying to piece together a meal? I’ve been there too. Just last week, I’d used up all my chicken breast for a keto casserole with broccoli, and there was nothing thawed or defrosted. My inner voice was screaming, “What now?” That’s when I remembered my trusty pantry staple: canned tuna.
With a few veggies in the fridge and some basic keto-friendly ingredients, I threw together this keto tuna casserole. It’s creamy, cheesy, and packed with flavor. Plus, I love it when I whip up something so quick and easy, and my husband goes, “Oh, this looks like a lot of effort.” I just nod my head in agreement. hehe
And I really hope you have some fresh or even dried dill on hand because fish and dill are a match made in heaven. But, if you don’t, any dry herb will do.
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Why You’ll Love This Recipe
This dish has all the good old classic flavors of a traditional tuna casserole but with a low-carb twist. It’s perfect for anyone following a keto diet or looking for an easy recipe to whip up after a long day.
Here’s why it’s a keeper:
Low-carb comfort food: Packed with healthy fats, protein, and veggies.
Customizable: Don’t have cauliflower? Use cabbage or zucchini noodles instead. Prefer mozzarella cheese? Go ahead!
Meal prep-friendly: Make it ahead and enjoy it throughout the week.
Simple ingredients: No need for anything fancy—just pantry staples, fresh veggies and a generous amount of cream and cheese (best part about keto, right?!).
Nutritional Benefits of Tuna
Tuna is one of those ingredients that works beautifully in low-carb recipes like this one. Here’s why it’s such a great choice:
High Protein & Low Carbs
Tuna is naturally high in protein and contains virtually no carbs—perfect for anyone following a low-carb keto lifestyle.
Rich in Nutrients
It’s loaded with B vitamins (for energy), selenium (an antioxidant), potassium (for heart health), and omega-3 fatty acids that support brain function.
Selecting the Best Tuna
When choosing tuna for your keto casserole, keep these tips in mind:
Types of Tuna
Skipjack or light tuna: Lower in mercury, making it a safer choice for regular consumption.
Solid white albacore tuna: Richer flavor but higher in mercury; enjoy occasionally.
Sustainability
Look for labels indicating “sustainably caught” or “pole-caught.” The Marine Stewardship Council (MSC) stamp is a good indicator of sustainable fishing practices.
Tuna Packing Options
Water-packed: Lower in calories, ideal for weight management.
Oil-packed: More flavorful, but higher in calories.
Addressing Mercury Concerns
Mercury in tuna is a valid concern, but you can minimize risks:
Choose lower-mercury options: Opt for skipjack or light tuna over albacore or yellowfin.
Limit consumption: Follow FDA guidelines for tuna intake based on your age and health status.
Diversify your fish intake: Include other low-mercury fish like salmon, sardines, or mackerel in your diet.
Check for “tested for mercury” labels on packaging.
Remember, the benefits of consuming tuna as part of a balanced diet typically outweigh the risks for most people.
Keto Tuna Casserole Recipe
Equipment
Ingredients
Main ingredients
- 2 cans 5 oz / 140g each tuna in olive oil or spring water, drained
- 2 cups 200g cauliflower or cabbage, chopped (both work great, it's totally up to you)
- 1/4 cup 30g peas
- 1/2 cup 60g chopped red peppers
- 1/4 cup 30g carrot, finely diced or shredded
- 1/4 cup 30g white onion, diced
- 1/2 cup Freshly copped dill or any herb of your choice
For the sauce:
- 2 tbsp 30g fresh dill, chopped (or 2 tsp dried)
- 1 cup 240ml / 240g heavy cream
- 1/2 cup 125g sour cream or cream cheese (it adds a bit of a tang)
- 1/2 cup 60g parmesan cheese, grated
- 1/2 cup 60g cheddar cheese, shredded
- 2 tbsp 30ml / 30g olive oil
- Salt sea salt preferred and black pepper to taste
Instructions
Oven Method
- Preheat your oven to 375°F (190°C).
- In a large bowl, combine the drained tuna, chopped vegetables, dill, salt, and pepper.
- Heat olive oil in an extra-large ovenproof skillet over medium heat.
- Add the tuna mixture and sauté vegetables for about 5 minutes until they soften slightly.
- Stir in heavy cream, sour cream or cream cheese, and parmesan cheese to create a creamy sauce mixture.
- Sprinkle cheddar cheese on top and transfer the skillet to the oven.
- Bake for 20–25 minutes until the cheese is golden and bubbly.
Pressure Cooker Method
- Follow steps 2–4 in your pressure cooker pot.
- Close the lid and cook on high pressure for 3 minutes.
- Quick-release the pressure and stir in cheddar cheese before serving.
Slow Cooker Method
- Mix all ingredients except cheddar cheese in your slow cooker.
- Cook on low for 3–4 hours or high for 1–2 hours.
- Add cheddar cheese during the last 30 minutes of cooking.
Notes
Nutrition
Tips for Success
Remove excess water: Pat your tuna dry with paper towels to avoid watery casserole sauce.
Extra veggies: Add green beans or green peppers if you have them on hand.
For picky eaters: Blend some of the veggies into the sauce mixture so they’re hidden but still nutritious.
Variations: Different Ways to Customize
This keto tuna casserole is versatile! Here are some ideas:
Swap cauliflower rice for shirataki noodles or zucchini noodles.
Add cream cheese or sour cream for an ultra-creamy texture.
Try mozzarella cheese instead of cheddar.
Use chicken broth instead of heavy cream if you prefer a lighter sauce.
Storage & Meal Prep
This healthy tuna casserole is ideal for meal prep:
Store leftovers in an airtight container in the fridge for up to 3 days. I love my Pyrex Glass Baking Dish as I can bake in it and it comes with air tight lid which means I don’t have to move my casserole into another dish for refrigeration.
Reheat in the oven or microwave until heated through.
If you’re prepping ahead of time, assemble everything except the cheese topping and store it in your baking dish until ready to cook.
This keto tuna casserole is more than just an easy recipe—it’s part of a long list of keto comfort foods that make sticking to your low-carb diet enjoyable. It has all the good old classic flavors without any extra carbs from egg noodles or bread crumbs.
For me, it brings back childhood memories of cheesy casseroles my family made growing up—though this version skips potato chips on top! Whether you’re cooking for yourself or feeding picky eaters at home, this dish checks all the boxes: simple ingredients, creamy texture, and plenty of flavor.
So next time you’re craving something hearty but keto-friendly, give this great recipe a try! It might just become your favorite recipe for busy weeknights.
Happy cooking!
