Shrimp Mushroom Casserole

The first time I made this shrimp casserole was actually on a rainy Tuesday when I had unexpected guests coming over. I scrambled through my kitchen and discovered some shrimp in the freezer and mushrooms that needed to be used. That impromptu dinner turned into such a hit that my friends started requesting it for every gathering. Something about bubbling cheese and tender shrimp just makes people feel cared for.

I once served this at a potluck where everyone was supposed to bring something fancy and expensive. This humble casserole disappeared first, with people actually scraping the dish. One friend admitted she usually hates cooked shrimp but went back for seconds. Theres something about the way the sour cream mingles with the earthy mushrooms that creates pure comfort.

Ingredients

• 450 g (1 lb) large shrimp: Fresh or thawed frozen work equally well, just pat them dry before cooking to prevent excess moisture
• 250 g (8 oz) cremini or button mushrooms: These develop a beautiful golden color when sautéed properly, adding depth to every bite
• 1 small onion: Finely chopped so it melts into the sauce rather than staying in distinct pieces
• 2 cloves garlic: Minced fresh releases more aromatic oils than pre-minced versions
• 2 tablespoons chopped fresh parsley: Adds a bright herbal counterpoint to the rich creamy sauce
• 120 g (1/2 cup) sour cream: The secret ingredient that makes this sauce impossibly rich without being heavy
• 120 ml (1/2 cup) whole milk: Creates the perfect consistency without overwhelming the other flavors
• 60 g (1/2 cup) shredded mozzarella cheese: Melts beautifully and creates those tempting cheese pulls
• 30 g (1/4 cup) grated Parmesan cheese: Adds a salty umami punch that elevates the entire dish
• 2 tablespoons unsalted butter: Used for both cooking the vegetables and greasing the baking dish
• 2 tablespoons olive oil: Helps the vegetables caramelize rather than steam in the pan
• 2 tablespoons all-purpose flour: Just enough to thicken the sauce without making it pasty
• 1 teaspoon paprika: Adds a subtle warmth and beautiful golden color to the sauce
• 1 teaspoon salt: Essential to bring out all the flavors in the creamy base
• 1/2 teaspoon black pepper: Freshly ground provides the best aromatic punch
• 1/2 teaspoon dried thyme: Earthy and herbaceous, pairs perfectly with both shrimp and mushrooms
• 80 g (3/4 cup) panko breadcrumbs: Creates the irresistible crispy topping everyone fights over
• 1 tablespoon melted butter: Tossed with the panko for golden, buttery crunch

Instructions

Preheat and prepare:

Heat your oven to 190°C (375°F) and butter a 1.5 to 2 quart casserole dish thoroughly

Sauté the aromatics:

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

Golden mushrooms:

Add sliced mushrooms and sauté for approximately 5 minutes until they turn golden brown, then stir in garlic for 1 more minute until fragrant

Build the base:

Sprinkle flour over the vegetables while stirring constantly to coat everything, cook for 1 minute to remove the raw flour taste

Create the sauce:

Gradually pour in milk while whisking to prevent lumps, add sour cream and spices, then simmer for 2 to 3 minutes until thickened enough to coat a spoon

Add the shrimp:

Stir in shrimp and cook for just 2 minutes until they start turning pink, they will finish cooking in the oven so do not overcook now

Assemble:

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

The crispy topping:

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

Bake to perfection:

Bake uncovered for 20 to 25 minutes until the sauce is bubbling up around the edges and the top is golden brown

Rest before serving:

Let the casserole sit for 5 minutes before serving, this helps the sauce set slightly and makes serving easier

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This casserole became my go-to for new parents because it reheats perfectly and freezes beautifully. I remember dropping one off at a neighbors house and she texted me later saying her husband ate three helpings. Sometimes the simplest meals bring the most joy to a tired family.

Choosing the Right Shrimp

I have learned that size matters more than you might think in this dish. Large shrimp hold up better during baking without becoming tough or rubbery. If you can only find smaller shrimp, reduce the initial cooking time to just one minute.

Mushroom Matters

Cremini mushrooms offer more flavor than plain white buttons but either works perfectly here. The key is not crowding the pan when sautéing, or they will steam instead of developing those gorgeous golden edges. Take your time with this step.

Make Ahead Magic

This casserole can be assembled completely up to 24 hours before baking. Just cover tightly and refrigerate, then add 5 to 10 minutes to the baking time if going straight from the refrigerator. The topping stays crispier if added just before baking rather than the night before.

• Let the dish come to room temperature for 20 minutes before baking if possible
• Cover with foil for the first 15 minutes if baking from cold, then uncover
• The internal temperature should reach 74°C (165°F) for food safety

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There is something deeply satisfying about serving a bubbling casserole that brings everyone to the table. This dish has become my comfort food go to for good reason.

Recipe FAQs

→ Can I use frozen shrimp instead of fresh?

Yes, thaw frozen shrimp completely and pat them dry before adding to the sauce. This prevents excess moisture from thinning your creamy mixture.

→ What type of mushrooms work best?

Cremini or button mushrooms are ideal for their earthy flavor and firm texture. Portobello mushrooms also work well for a meatier bite.

→ Can I make this ahead of time?

Assemble everything up to step 7, cover tightly, and refrigerate for up to 24 hours. Add the topping just before baking and increase baking time by 5-10 minutes.

→ What sides complement this casserole?

A crisp green salad with vinaigrette balances the richness perfectly. Steamed rice, roasted vegetables, or crusty bread also make excellent accompaniments.

→ How do I know when the shrimp are done?

The shrimp should be pink and opaque. Since they continue cooking in the oven, remove them from the skillet when just beginning to turn pink to prevent overcooking.

→ Can I substitute the dairy components?

For a lighter version, use Greek yogurt instead of sour cream. For lactose-free options, try lactose-free dairy products or a creamy cashew blend.