Shrimp Mushroom Casserole

The first time I made this shrimp mushroom casserole, it was supposed to be a quick weeknight dinner but ended up being the dish my sister requested for every family gathering afterward. The way the creamy sauce bubbles up through the golden panko topping creates this incredible contrast that makes everyone lean in a little closer when it comes out of the oven.

Last winter, I made this for a friend who swore she hated casserooles because they reminded her of gloppy school lunches. She actually went back for thirds and asked for the recipe before she even left my apartment. Something about the fresh herbs and real sour cream instead of canned soup makes all the difference.

Ingredients

• 450 g (1 lb) large shrimp: Peeled and deveined saves precious time, and buying them already prepped means you can focus on getting that sauce just right
• 250 g (8 oz) cremini or button mushrooms: Cremini have more flavor than button mushrooms, but either works beautifully here
• 1 small onion: Finely chopped so it practically melts into the sauce without any noticeable chunks
• 2 cloves garlic: Minced fresh because garlic powder would miss that aromatic punch that hits you when you first lift the lid
• 2 tablespoons chopped fresh parsley: Adds brightness and makes everything taste fresher, plus it looks gorgeous sprinkled on top
• 120 g (1/2 cup) sour cream: This is the secret ingredient that makes the sauce taste luxurious instead of just creamy
• 120 ml (1/2 cup) whole milk: Whole milk creates that velvety texture you want, though you can get away with 2% if needed
• 60 g (1/2 cup) shredded mozzarella cheese: Melts into beautiful strands and gives the sauce that satisfying stretch
• 30 g (1/4 cup) grated Parmesan cheese: Brings a salty, nutty depth that balances the mild mozzarella perfectly
• 2 tablespoons unsalted butter: One for sautéing the vegetables, one saved for greasing the dish
• 2 tablespoons olive oil: Helps prevent the butter from burning while you cook the aromatics
• 2 tablespoons all-purpose flour: Just enough to thicken the sauce without making it heavy or pasty
• 1 teaspoon paprika: Adds a subtle warmth and beautiful color to the cream sauce
• 1 teaspoon salt: Enhances all the flavors without overpowering the delicate shrimp
• 1/2 teaspoon black pepper: Freshly cracked gives you those little sparks of heat throughout
• 1/2 teaspoon dried thyme: Earthy and aromatic, thyme pairs so naturally with both mushrooms and seafood
• 80 g (3/4 cup) panko breadcrumbs: Panko stays crunchier longer than regular breadcrumbs, which is crucial for that topping
• 1 tablespoon melted butter: Tossed with the panko to help it turn golden and create those crispy edges everyone fights over

Instructions

Get your oven ready:

Preheat to 190°C (375°F) and butter your casserole dish thoroughly, paying special attention to the corners where things love to stick.

Sauté the aromatics:

Heat olive oil and 1 tablespoon butter in a large skillet over medium heat, cook the onion until soft and translucent, about 3 minutes.

Add the mushrooms:

Throw in the sliced mushrooms and let them cook undisturbed for a couple minutes so they get nicely golden before stirring, about 5 minutes total.

Bring in the garlic:

Add the minced garlic and cook for just 1 minute until fragrant, being careful not to let it brown or it will turn bitter.

Make your roux:

Sprinkle the flour over the vegetables and stir constantly for 1 minute to cook out the raw flour taste.

Build the sauce:

Pour in the milk gradually while whisking, then add sour cream, paprika, salt, pepper, and thyme, simmering until thickened.

Add the shrimp:

Stir in the shrimp and cook for just 2 minutes until they start turning pink, knowing they will finish in the oven.

Cheese and herbs:

Fold in mozzarella, half the Parmesan, and parsley, then pour everything into your prepared baking dish.

Make the topping:

Mix panko with melted butter and remaining Parmesan, then sprinkle evenly over the casserole.

Bake until golden:

Bake uncovered for 20 to 25 minutes until bubbly and the topping is deep golden brown.

Let it rest:

Wait 5 minutes before serving so the sauce has a chance to set slightly and makes serving much easier.

Save

This became my go-to for new parents and anyone needing a comforting meal during tough times. There is something about this dish that feels like a warm hug, and it travels surprisingly well if you need to bring it somewhere.

Making It Ahead

You can assemble the entire casserole up to a day ahead and keep it covered in the refrigerator. Just add an extra 5 to 10 minutes to the baking time since it will be cold going into the oven.

Freezing Instructions

Wrap the unbaked casserole tightly with foil and freeze for up to 2 months. Thaw overnight in the refrigerator before baking, or bake from frozen adding about 20 extra minutes and covering with foil if the top browns too quickly.

Serving Suggestions

This casserole is rich enough that it really shines with something fresh and acidic alongside it. A crisp green salad with a bright vinaigrette helps cut through the creaminess perfectly.

• Steamed green beans with lemon make a lighter side that still feels substantial
• Crusty bread is perfect for soaking up any extra sauce on your plate
• A glass of chilled white wine brings everything together beautifully

Save

There is nothing quite like watching people take that first bite and seeing their eyes light up. This is the kind of comfort food that turns an ordinary Tuesday into something worth remembering.

Recipe FAQs

→ Can I make this ahead of time?

Yes, assemble the casserole up to 24 hours in advance and refrigerate. Add an extra 5-10 minutes to baking time if cooking from cold.

→ What other seafood works well?

Scallops, lump crab meat, or cubed white fish like cod or halibut make excellent substitutions for shrimp.

→ Can I freeze leftovers?

Leftovers freeze well for up to 2 months. Thaw overnight in the refrigerator and reheat at 180°C until warmed through.

→ How do I know when shrimp are done?

Shrimp turn pink and opaque when cooked. Since they finish cooking in the oven, remove them from the skillet when just beginning to curl and turn pink.

→ What sides pair well?

Steamed rice, crusty bread, roasted green beans, or a crisp green salad complement the rich, creamy texture beautifully.

→ Can I use frozen shrimp?

Absolutely. Thaw frozen shrimp completely in the refrigerator and pat dry before adding to the skillet to prevent excess moisture.