Name: Cheesy KETO TUNA CASSEROLE: Easy, Low Carb Comfort Food
Prep time: 10 min
Cook time: 20 min
Total time: 35 min
Ingredients: 4 tbsp Butter (Substitution: Olive oil can be used for a dairy-free option.); 0.5 pieces Onion, chopped (Use yellow or white onion for optimal flavor.); 2 cups Mushrooms, sliced (Substitution: Portobello or cremini mushrooms recommended.); 1 cup Spinach, chopped (Substitution: Fresh or frozen spinach can be used; if using frozen, thaw and drain well.); 2 cans Tuna, drained (Any brand of tuna in water works well.); 1 cup Mozzarella Cheese, grated (Substitution: Use shredded or fresh mozzarella.); 1 cup Cream Cheese, cubed (Soften for easier mixing.); 1 tsp Italian Seasoning (Substitution: Use a blend of dried basil, oregano, and thyme if unavailable.); Salt and Pepper, to taste (Adjust according to personal preference.); 2 cups Cheddar Cheese, shredded (Substitution: Choose a sharp or mild cheddar based on taste preference.); 2 tbsp Almond Flour (Substitution: Coconut flour may work but may alter taste.); Parmesan Cheese (For an extra cheesy flavor sprinkle on top after baking.)

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The moment I walked into my kitchen to prepare dinner, I was hit with the comforting smell of something creamy and cheesy cooking away. After a long day, nothing feels more satisfying than a hearty meal that doesn’t require hours of prep. That’s when I decided to whip up my go-to Keto Tuna Casserole, a delightful dish that’s both indulgent and mindful of my carb intake.

This recipe not only elevates the humble tuna but transforms it into a health-conscious delight packed with nutritious mushrooms and vibrant spinach, all while keeping those pesky carbs at bay. Imagine diving into a bowl of cozy goodness that’s ready in under 30 minutes—a perfect solution for busy weeknights! With just 3 net carbs per serving, you can savor every bite without a second thought. Trust me, this casserole is bound to become your new family favorite!

Why You’ll Adore This Keto Tuna Casserole

Heavenly Comfort Food: This casserole brings you rich, cheesy goodness without the carbs, creating a fulfilling meal for everyone at the table.
Quick & Easy: Ready in under 30 minutes, it’s perfect for busy weeknights. Spend less time cooking and more time enjoying!
Nutritious Ingredients: Loaded with mushrooms and spinach, it offers a healthy twist without compromising on flavor.
Versatile Dish: Feel free to swap in your favorite vegetables or add spices for an extra kick!
Family-Friendly: Even picky eaters will love this dish, making it a sure hit for family dinners.
For tips on enhancing flavor, don’t forget to check out our expert suggestions!

Keto Tuna Casserole Ingredients

For the Casserole
• Butter – Adds richness and aids in sautéing vegetables. Substitution: Olive oil can be used for a dairy-free option.
• Onion (½, chopped) – Provides aromatic flavor and sweetness. Prep Note: Use yellow or white onion for optimal flavor.
• Mushrooms (2 cups, sliced) – Serves as the low-carb base instead of traditional noodles, adding bulk and nutrients. Substitution: Portobello or cremini mushrooms recommended.
• Spinach (1 cup, chopped) – Offers color and a boost of vitamins. Substitution: Fresh or frozen spinach can be used; if using frozen, thaw and drain well.
• Tuna (2 cans, drained) – Main protein source, providing flavor and texture. Prep Note: Any brand of tuna in water works well.
• Mozzarella Cheese (1 cup, grated) – Contributes creaminess and a melty texture. Substitution: Use shredded or fresh mozzarella.
• Cream Cheese (1 cup, cubed) – Creates a creamy base that binds the casserole. Prep Note: Soften for easier mixing.
• Italian Seasoning (1 tsp) – Enhances overall flavor profile. Substitution: Use a blend of dried basil, oregano, and thyme if unavailable.
• Salt and Pepper (to taste) – Essential for flavor enhancement. Note: Adjust according to personal preference.
• Cheddar Cheese (2 cups, shredded) – Top layer for added cheesiness and crunch. Substitution: Choose a sharp or mild cheddar based on taste preference.
• Almond Flour (2 tbsp) – Provides a traditional casserole topping texture while keeping it low-carb. Substitution: Coconut flour may work but may alter taste.

Optional Topping
• Parmesan Cheese (optional) – For an extra cheesy flavor sprinkle on top after baking. Note: Adds a delightful richness to your Keto Tuna Casserole.

How to Make Keto Tuna Casserole

Preheat Oven: Begin by setting your oven to 350°F (176°C). While it warms up, generously coat a 9×9 inch baking dish with cooking spray to prevent sticking.
Prep Vegetables: Chop the spinach and onion, and slice the mushrooms. Having everything ready will make cooking a breeze and keep your workflow smooth!
Sauté Vegetables: In a large pan over high heat, melt the butter. Add the chopped onions and sauté for about 3 minutes until they soften. Next, toss in the sliced mushrooms and cook for 5 minutes. You want them to release their moisture. Finally, stir in the spinach until wilted, then reduce the heat to low.
Combine Ingredients: Now, add in the cubed cream cheese, grated mozzarella, Italian seasoning, salt, and pepper. Stir everything together until the cheese begins to melt. Carefully mix in the drained tuna until it’s well combined.
Assemble and Bake: Spoon the delightful mixture into your prepared baking dish. Top with shredded cheddar and the almond flour for a nice crispy finish. Bake in the oven for 15-20 minutes, until the top is golden brown and bubbly. Let it cool slightly before serving to enhance those delicious flavors!

Optional: Sprinkle extra parmesan cheese on top after baking for a delightful cheesy finish.

Exact quantities are listed in the recipe card below.

What to Serve with Keto Tuna Casserole?

Imagine a cozy family dinner filled with comforting flavors and heartwarming aromas while you enjoy a satisfying meal that feels indulgent yet guilt-free.

Fresh Garden Salad: Crisp greens tossed in a light vinaigrette serve as a perfect counterbalance to the richness of the casserole.
Roasted Vegetables: Colorful seasonal veggies roasted to perfection add an appealing crunch and additional nutrients to your plate.
Garlic Breadsticks: For those who aren’t following keto, cheesy garlic breadsticks pair beautifully, offering a delightful contrast.
Steamed Green Beans: Tender green beans provide a nice crunch and earthy flavor that complements the casserole’s creamy texture.
Creamy Cauliflower Mash: This keto-friendly alternative to mashed potatoes is smooth, buttery, and perfectly pairs with your casserole for a hearty side.
Zucchini Noodles: Light and refreshing, they add a unique twist to the plate while keeping with the low-carb theme.
Sparkling Water with Lemon: Refreshing and light, this drink cleanses the palate and ensures a delightful dining experience.
Chocolate Avocado Mousse: For dessert, this rich yet healthy option is a creamy delight that’s a great way to end your meal without the carbs.

Keto Tuna Casserole Variations

Customize this delightful dish to make it your own, and tantalize your taste buds with exciting twists!

Vegetable Boost: Add broccoli or cauliflower for additional nutrients and a different texture. They hold up well in the bake, integrating beautifully with the flavors.
Creamier Layer: Swap cream cheese for ricotta cheese to create a lighter, fluffier filling. Ricotta offers a lovely creaminess that’s hard to resist!
Cheesy Inferno: Stir in jalapeños or crushed red pepper flakes for a spicy kick. The heat will enhance the rich flavors and provide a delightful zing.
Herb Infusion: Incorporate fresh herbs like parsley or dill for a fresh, aromatic layer. These herbs can elevate the dish and add brightness to every bite.
Protein Variation: Swap out tuna for shredded chicken or salmon to change things up. Either option lends a unique flavor while keeping the dish hearty and satisfying.
Nut-Free Crunch: Top with crushed pork rinds instead of almond flour for an irresistible crispy texture. This gives a fun crunch that complements the creamy filling well.
Dairy-Free Delight: Use nut cheese or cashew cream for a fully dairy-free option, ensuring everyone at the table can enjoy a comforting portion.
Zesty Twist: Mix in some sour cream or a bit of lemon juice for a zesty kick, adding a delightful tang to offset the richness of the cheese.

With these variations, your Keto Tuna Casserole can take on new identities, ensuring it never feels monotonous and always delights!

How to Store and Freeze Keto Tuna Casserole

Fridge: Store leftovers in an airtight container for up to 3 days. This helps maintain the dish’s creamy texture and flavor while ensuring it’s ready for your next meal.

Freezer: Your keto tuna casserole can be frozen in a freezer-safe container for up to 6 months. Be sure to cool it completely before freezing to preserve its delightful taste and texture.

Reheating: Thaw in the fridge overnight before reheating. When ready, bake at 350°F (176°C) until warmed through, about 20 minutes. For a quicker option, you can also reheat from frozen, but expect longer cooking times.

Planning Ahead: Prepare a double batch for quick and easy weeknight dinners! Enjoy the rich flavors of this keto tuna casserole even on your busiest days.

Make Ahead Options

These Keto Tuna Casserole is perfect for meal prep enthusiasts looking to save time during busy weeknights! You can chop the vegetables (onion, mushrooms, and spinach) and combine the casserole ingredients up to 24 hours in advance. Simply refrigerate the prepared mixture in an airtight container to maintain freshness and prevent browning. When you’re ready to serve, transfer the mixture to your baking dish, sprinkle on the cheese and almond flour, then bake at 350°F (176°C) for 15-20 minutes until golden and bubbly. This way, you can enjoy a delicious, homemade casserole with minimal effort—just as satisfying and comforting as when made fresh!

Expert Tips for Keto Tuna Casserole

Use Fresh Ingredients: Fresh mushrooms and spinach will enhance flavor and texture. Avoid canned options if possible; the freshness makes a difference in your keto tuna casserole.
Shred Your Own Cheese: Pre-shredded cheese contains fillers that can add carbs. Shredding your mozzarella ensures a creamy texture without extra carbohydrates.
Don’t Overcook Tuna: Since canned tuna is already cooked, add it at the end of the cooking process to maintain its delicate texture and flavor in the casserole.
Control Seasoning: Taste and adjust salt and pepper as needed. Remember, some cheese varieties are saltier than others, so sample before adding more seasoning.
Experiment with Veggies: Feel free to swap out spinach or mushrooms for seasonal vegetables like zucchini or bell peppers; this keeps your keto tuna casserole exciting and nutritious!

Keto Tuna Casserole Recipe FAQs

What type of mushrooms should I use?
Absolutely! For the best results, I recommend using cremini or portobello mushrooms as they add depth and flavor. If you can’t find those, button mushrooms work just fine but may be milder in taste.

How should I store leftovers?
Leftovers can be saved in an airtight container in the refrigerator for up to 3 days. To maintain the creamy texture, allow the casserole to cool completely before transferring it to the fridge.

Can I freeze Keto Tuna Casserole?
Yes, you can definitely freeze this dish! Portion it into freezer-safe containers and it will last for up to 6 months. Just be sure to let it cool to room temperature before sealing it up. To reheat, thaw in the fridge overnight and then bake at 350°F (176°C) until heated through, which should take about 20 minutes.

What if my casserole is too watery?
If your casserole turns out too watery, it could be due to excess moisture from the mushrooms. To remedy this, sauté the mushrooms longer to allow more moisture to evaporate before adding them to the mix. You can also add a bit more almond flour to help absorb excess liquid.

Are there any dietary considerations for pets?
Great question! While tuna is safe for humans, it should be given in moderation to pets. Always consult your vet before introducing new foods into your pet’s diet, as ingredients like onion can be harmful to dogs and cats.

Can this recipe be adjusted for other dietary needs?
Very much so! If you or someone you know has a gluten allergy, simply ensure all ingredients are certified gluten-free. As for a dairy-free version, substitute dairy products with alternatives like coconut cream and nutritional yeast for a cheesy flavor without the dairy.