Easy Instant Pot Trout Casserole Recipe

Dinner, Seafood

March 29, 2026

Tired of the same old weeknight dinners? Shake things up with this incredibly simple and elegant Instant Pot Trout Casserole. It’s a one-pan wonder packed with flaky trout, vibrant vegetables, and aromatic herbs. This recipe delivers a healthy, low-carb, and deeply satisfying meal with minimal effort. The Instant Pot does all the heavy lifting, steaming everything to perfection, while an optional final bake gives it a beautiful finish. Get ready to add a new favorite to your dinner rotation!

Ingredients

• 1 lb / 450g trout fillets, skinless
• 1 cup / 150g cherry tomatoes, halved
• ½ medium zucchini, sliced
• 1 cup / 100g cauliflower florets
• 1 small onion, sliced
• 4 tbsp olive oil, divided
• 2 tsp sea salt
• 1 tsp dried rosemary
• 1 tsp dried thyme
• ½ tsp garlic powder

Instructions

1. Directions
2. Prepare the Pan: Line a small square pan that fits inside your Instant Pot with parchment paper. Drizzle with 2 tablespoons of olive oil.
3. Layer the Vegetables: Arrange the sliced onions on the bottom of the pan. Create the next layer with sliced zucchini, followed by the cauliflower florets and halved cherry tomatoes. Sprinkle with half of the sea salt and drizzle with the remaining 2 tablespoons of olive oil.
4. Add the Trout: Place the trout fillets on top of the vegetables. Season the fish evenly with the remaining sea salt, dried rosemary, dried thyme, and garlic powder.
5. Seal for Cooking: Tightly cover the pan with aluminum foil to lock in the steam and flavors.
6. Set Up the Instant Pot: Pour 2 cups of water into the inner pot. Place the trivet inside and carefully set your prepared pan on top of it.
7. Pressure Cook: Secure the lid and turn the steam release handle to the ‘Sealing’ position. Select the ‘Manual’ or ‘Pressure Cook’ setting and cook on high pressure for 20 minutes.
8. Release Pressure: Once the cooking cycle is complete, perform a quick pressure release by carefully turning the handle to the ‘Venting’ position. Once the pin drops, open the lid.
9. Optional Crispy Finish: For a golden, roasted finish, preheat your oven to 450°F / 230°C. Carefully remove the pan from the Instant Pot, discard the aluminum foil, and bake for 10-15 minutes, or until the top is lightly browned.
10. Serve: Let the casserole cool slightly before serving immediately.

Nutritional Information

• Nutrition Per Serving
• Calories: 361
• Total Fat: 23.8g
• Net Carbs: 3.7g
• Protein: 31.6g
• Fiber: 1.8g

Pro Tips

• Swap the Veggies: Feel free to substitute with other quick-cooking vegetables like bell peppers, asparagus, or green beans.
• Fresh Herb Boost: If you have fresh herbs, use 1 tablespoon of fresh rosemary or thyme instead of 1 teaspoon dried for a more vibrant flavor.
• Add a Citrus Kick: Squeeze a wedge of fresh lemon over the finished casserole just before serving to brighten up all the flavors.
• Don’t Skip the Foil: Covering the pan tightly with foil is crucial. It prevents water from the Instant Pot from getting into your casserole and ensures the fish steams perfectly instead of boiling.

FAQ

Q: Can I use frozen trout for this recipe
A: For the best results and texture, it’s recommended to use thawed trout fillets. If using frozen, make sure to thaw them completely and pat them dry with a paper towel before seasoning and cooking.

Q: What other fish can I use instead of trout
A: This recipe is versatile and works well with other flaky fish like salmon, cod, or haddock. Cooking times may vary slightly depending on the thickness of the fish fillets.

Q: Is the final baking step necessary
A: No, the final bake is completely optional. The dish is fully cooked in the Instant Pot. The oven step is only to give the casserole a golden, slightly crispy finish. You can serve it directly after pressure cooking.

Q: What if I don’t have a pan that fits in my Instant Pot
A: If you don’t have a suitable pan, you can create a foil boat. Use a large piece of heavy-duty aluminum foil, shape it into a pan-like container with raised sides, and place it on the trivet. This will hold all the ingredients and work just as well.

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