Keto Fish Casserole layers white fish over charred broccoli, scallions, and capers, then bathes everything in a Dijon cream sauce dotted with butter. It bakes until the fish turns opaque and the sauce bubbles around the edges. It's pure comfort food with 41g of protein per serving.
This dish is a powerhouse of healthy fats and high-quality protein, perfectly balanced for a ketogenic lifestyle. By sautéing the vegetables first, we lock in texture and flavor before the final bake.
Ingredients
- 25 oz (708g) white fish (such as cod, halibut, or tilapia), sliced into fillets
- 15 oz (425g) broccoli florets
- 3 oz (85g) unsalted butter, divided
- 6 scallions (approx. 2 oz / 56g), chopped
- 1.25 cups (300ml) heavy whipping cream
- 2 tbsp (30g / 1.06 oz) small capers, drained
- 1 tbsp (4g / 0.14 oz) dried parsley
- 1 tbsp (15g / 0.53 oz) Dijon mustard
- 0.25 tsp (0.5g / 0.02 oz) black pepper
- 1 tsp (6g / 0.21 oz) salt
- 2 tbsp (30ml) olive oil
- 5 oz (140g) leafy greens (spinach or kale)
Directions
- Preheat the oven to 400°F (200°C) and ensure your baking tray is ready.
- Heat 2 tbsp (30ml) olive oil in a large saucepan over medium-high heat until shimmering.
- Add the 15 oz (425g) broccoli florets to the hot oil and fry for 5.0 minutes, stirring occasionally until slightly charred and tender-crisp.
- Remove the florets from the pan, season with a pinch of the salt and pepper, and set aside.
- In the same saucepan, add the 6 chopped scallions and 2 tbsp (30g / 1.06 oz) capers, frying for 2.0 minutes until fragrant; return the broccoli to the pan and toss to combine.
- Grease a medium baking tray with 0.5 oz (14g) of the butter and spread the fried vegetable mixture evenly across the bottom.
- Arrange the 25 oz (708g) of sliced fish on top of the vegetables, nestling the pieces into the gaps for even cooking.
- In a small bowl, whisk together 1.25 cups (300ml) heavy cream, 1 tbsp (15g / 0.53 oz) Dijon mustard, and 1 tbsp (4g / 0.14 oz) dried parsley, then pour the mixture over the fish and vegetables.
- Top the dish with the remaining 2.5 oz (71g) of butter (cut into small cubes) and the 5 oz (140g) of leafy greens; bake for 25.0 to 30.0 minutes until the fish is opaque and the sauce is bubbling.
Nutritional Information (Per Serving)
- Calories: 822 kcal
- Total Carbs: 9g (0.32 oz)
- Net Carbs: 7g (0.25 oz)
- Protein: 41g (1.45 oz)
- Fat: 69g (2.43 oz)
Pro Tips for the Perfect Casserole
- Pat the Fish Dry: Before slicing and adding your white fish to the tray, use a paper towel to pat it completely dry. This prevents excess moisture from releasing during the bake, ensuring your sauce stays thick and creamy rather than watery.
- Temper the Cream Mixture: Whisk your heavy cream and Dijon mustard at room temperature. Cold cream can sometimes cause the butter to clump or the sauce to break when it first hits the hot oven.
- Don't Overcook the Broccoli: When frying the florets in olive oil, look for a bright green color with just a hint of char. They will finish softening in the oven; overcooking them in the pan leads to a mushy texture in the final dish.
- Choose High-Fat Dairy: For the best keto results and a stable sauce, always use heavy whipping cream (at least 36% fat). Lower-fat alternatives lack the viscosity needed to coat the fish and veggies properly.
Frequently Asked Questions (FAQ)
What is the best type of fish to use for this Creamy Keto Fish Casserole? For the best results, use firm white fish such as cod, halibut, sea bass, or tilapia. These varieties hold their shape well during the 30-minute baking process and soak up the flavors of the creamy mustard sauce without becoming overly oily.
Can I make this keto fish casserole ahead of time? Yes! You can prep the vegetables and the cream mixture up to 24 hours in advance. Store them separately in the refrigerator. When you are ready to eat, assemble the tray with fresh fish and bake as directed. We do not recommend freezing the unbaked casserole, as the cream sauce may separate.
How do I store and reheat leftovers? Store any leftover casserole in an airtight container in the refrigerator for up to 3 days. To reheat, place a portion in an oven-safe dish at 350°F (180°C) until warmed through, or microwave on medium power. Avoid high heat to prevent the fish from becoming rubbery.
Can I use frozen broccoli for this recipe? You can use frozen broccoli, but you must thaw it completely and squeeze out all excess water before frying. Frozen vegetables contain more moisture than fresh, which can dilute the creamy sauce if not properly drained.
Pro Tips
- Pat the white fish completely dry before slicing and arranging it on the tray. Dry fish doesn't release extra water, so the sauce stays thick and creamy instead of going watery.
- Fry the broccoli only until it's bright green with a hint of char. It finishes softening in the oven, and overcooking it in the pan leads to a mushy casserole.
- Whisk the heavy cream and Dijon mustard at room temperature. Cold cream can make the butter clump or the sauce break when it meets the hot oven.
- Use heavy whipping cream with at least 36% fat. Lighter dairy lacks the viscosity to coat the fish and vegetables and won't give you the keto macros either.
- Nestle the fish pieces into the gaps of the vegetable layer so every portion cooks evenly in the sauce.
Frequently Asked Questions
Which white fish should I use?
The recipe calls for white fish such as cod, halibut, or tilapia. Slice it into fillets that cook through in the 25-30 minute bake.
Can I make this casserole ahead of time?
You can fry the vegetables and whisk the cream sauce earlier in the day, then assemble the tray and bake when you're ready to eat.
Can I use milk instead of heavy cream?
Heavy cream is what gives the sauce its body. A lighter dairy will thin out in the oven and won't coat the fish and broccoli properly.
Is this fish casserole keto?
It fits squarely in a keto day: each serving has 9g total carbs and 7g net carbs, with 41g of protein and 69g of fat from the cream and butter.
Recipe card below.
More Recipes You'll Love
- Instant Pot Mustard Pork with Mushrooms
- Secret Ingredient Juicy Umami Burgers (with Chicken Livers)
- Keto Pork Rind Cereal (Cinnamon Toast Crunch Style)
Ingredients
Method
- Preheat the oven to 400°F (200°C) and ensure your baking tray is ready.
- Heat 2 tbsp (30ml) olive oil in a large saucepan over medium-high heat until shimmering.
- Add the 15 oz (425g) broccoli florets to the hot oil and fry for 5. 0 minutes, stirring occasionally until slightly charred and tender-crisp.
- Remove the florets from the pan, season with a pinch of the salt and pepper, and set aside.
- In the same saucepan, add the 6 chopped scallions and 2 tbsp (30g / 1.06 oz) capers, frying for 2. 0 minutes until fragrant; return the broccoli to the pan and toss to combine.
- Grease a medium baking tray with 0. 5 oz (14g) of the butter and spread the fried vegetable mixture evenly across the bottom.
- Arrange the 25 oz (708g) of sliced fish on top of the vegetables, nestling the pieces into the gaps for even cooking.
- In a small bowl, whisk together 1. 25 cups (300ml) heavy cream, 1 tbsp (15g / 0.53 oz) Dijon mustard, and 1 tbsp (4g / 0.14 oz) dried parsley, then pour the mixture over the fish and vegetables.
- Top the dish with the remaining 2. 5 oz (71g) of butter (cut into small cubes) and the 5 oz (140g) of leafy greens; bake for 25. 0 to 30. 0 minutes until the fish is opaque and the sauce is bubbling.
- Pat the Fish Dry: Before slicing and adding your white fish to the tray, use a paper towel to pat it completely dry. This prevents excess moisture from releasing during the bake, ensuring your sauce stays thick and creamy rather than watery.
- Don't Overcook the Broccoli: When frying the florets in olive oil, look for a bright green color with just a hint of char. They will finish softening in the oven; overcooking them in the pan leads to a mushy texture in the final dish.
