This dish is so flavorful and a Southern classic, especially during the holidays.
My grandma used to make Oyster Casserole every Christmas. I was a pretty young Texan kid at the time, and oysters scared me a little. But I remember my sister and other family members just loved it. Now, the Loon and I can’t get enough of it. Try it, and you’ll see what we mean.
How To Make Oyster Casserole
This casserole is not difficult to prepare at all.
In fact, it can be prepared hours in advance and then baked just before serving (wait to add the bread crumbs until just before placing it in the oven).
As with many Southern dishes, especially Cajun recipes, this dish starts with the holy trinity of veggies: onion, celery, and green bell pepper.
Cook over medium heat in olive oil and butter until nice and tender.
EXPERT TIP: For added flavor, we throw in some chopped scallions (green onions) and garlic in the final 30 seconds of sautéing the veggies.
Selecting the Oysters
There are many types of oysters, fresh and packaged. For this recipe, we think the packaged variety is perfectly acceptable.
Packaged oysters are found at well-stock supermarkets in the seafood department, or at your local seafood market.
EXPERT TIP: You’ll end up draining the oysters twice for this casserole. First, when you remove them from the container. Drain and rinse them under the faucet in your sink. Add them with the mushrooms into the skillet. The mushrooms will soften and release liquid, along with the oysters. Thus, needing another draining (more on that in a bit).
A Bechamel Sauce Binds the Casserole Together
While the oysters are simmering, or even after they’ve simmered, it’s time to make an easy bechamel sauce.
In a medium-sized saucepan, melt a couple of tablespoons of butter over medium heat. Add two heaping tablespoons of flour and stir for 1 minute.
EXPERT TIP: The flour and butter mixture is called a roux. After adding half-and-half and other flavor enhancements, the liquid will thicken. This will take anywhere from 2 to 5 minutes. The sauce should be pretty thick, see video for reference. Now, add the Parmesan cheese to finish off the sauce.
Now, back to oysters and mushrooms: After 15 minutes of simmering, a decent amount of liquid will have released from the oysters and the mushrooms.
This is normal but you don’t want all this liquid in the casserole.
Simply place a colander over a large bowl, or in your sink, and carefully transfer the contents of the skillet into it. Once fully drained, return the satuéed veggies and oyster to the skillet, or the saucepan containing the bechamel sauce.
How To Make a Breadcrumb Topping
Like many casseroles, you’re going to want a nice crunchy topping.
Easy! Simply take a large loaf of bread, remove the crusts as best you can, and then pulverize in your food processor.
EXPERT TIP: If you don’t have a food processor, simply use a knife to chop the bread until you have coarse bread crumbs. We think thicker breadcrumbs are better anyway. Just before topping the casserole, melt a couple of tablespoons of butter and stir it into the breadcrumbs with a pinch of salt. Now, generously top the casserole with the prepared breadcrumbs.
When To Serve Oyster Casserole
As mentioned previously, this dish is a very popular one to serve during the holidays. It’s perfect alongside Best Mashed Potatoes, Mom’s Dressing, Gourmet Green Bean Casserole, and Corn Casserole!
But, we’ve got to tell you, this casserole is so flavorful and easy to prepare, we love having it all year long!
You may also like our Fried Oysters and Clams, or our BLT with Fried Oysters, too!
In the meantime, don’t you just want to sink your teeth into this?
If you’re trying to think of a side dish that’s a little different this holiday season (or anytime, for that matter), look no further!
We have found that even folks that aren’t big fans of oysters really love this dish.
I’m not sure how my Grandma who lived in central Missouri ever learned about oyster casserole, but my family is thankful that she did. Odds are, your family will be thanking you, too, when you bring it to the table. It’s that good!
Ready to make the best casserole this side of the Gulf of Mexico? Go for it!
And when you do, be sure to take a photo of it, post it on Instagram, and tag @HowToFeedaLoon and hashtag #HowToFeedaLoon!
- 2 tbsp olive oil
- 6 tbsp unsalted butter divided
- ½ cup onion chopped
- ½ cup green bell pepper seeded and chopped
- ½ cup celery chopped
- ¼ cup scallions sliced, white and green parts
- 3 cloves garlic minced
- 2 16 oz containers oysters fresh, drained and rinsed
- 8 oz mushrooms sliced
- 2 tbsp all-purpose flour heaping
- ½ cup half and half
- 1 tbsp fresh lemon juice
- 1 tbsp Worcestershire sauce
- 1 tbsp hot sauce
- ¼ cup Parmesan cheese grated
- 1 tsp Kosher salt
- ½ tsp freshly ground black pepper
- 1 cup breadcrumbs fresh, chopped from a loaf of bread with the crust mostly removed
- Preheat oven to 400°F.
- Heat the olive oil over medium-high heat in a large skillet. Stir in 2 tablespoons of the butter until melted. Add onion, bell pepper, and celery, and cook until soft, about 5 to 7 minutes. Add the scallions and garlic and cook for another minute.
- Add oysters and mushrooms and bring to a simmer, stirring often, 5 minutes. Set aside.
- Melt 2 tablespoons of the butter in a medium saucepan over medium heat. Whisk in flour, and cook, whisking constantly, until smooth, 1 minute.
- Stir in half and half, lemon juice, Worcestershire sauce, hot sauce, salt, and pepper, whisking constantly, until very thick and beginning to bubble, about 2 to 5 minutes. Stir in Parmesan cheese until melted, about 1 more minute.
- Using a fine-mesh sieve or colander, strain the oyster mixture, and discard the liquid.
- Add oyster mixture to cheese sauce and stir until fully incorporated.
- Spread mixture in an 11x7-inch baking dish.
- Melt the remaining 2 tablespoons of butter, then toss breadcrumbs with melted butter and a pinch of salt. Sprinkle the breadcrumbs over the oyster mixture.
- Bake for 15 minutes, or until bubbly. Remove the casserole from the oven and move the rack to the 2nd level under the broiler. Place the casserole under the broiler for 1 to 2 minutes, until the breadcrumb topping is slightly browned. Watch closely!!! Don't let burn, as broilers vary! Remove from oven and serve at once.
POST UPDATE: This recipe was originally published in December 2016, but was updated with improved tweaks to the recipe with new tips and photography, and a fabulous new video in December 2020!
I keep reading and rereading this mouthwatering recipe but I have one concern. If simmering the oysters with the mushrooms takes about 15 minutes and then baking the oysters again within the sauce for another 15 minutes aren’t the oysters going to be over cooked and chewy? During this food shortage period , oysters in Michigan are hard to come by and I don’t want to be disappointed if your recipe doesn’t yield plump juicy oysters along with the white/cheese sauce. I’m not being negative just cautious.
Hi Terrie! We completely understand! After sautéing the veggies, you’ll just add the oysters and mushrooms for 5 minutes (not 15). And then it all bakes for 15 minutes. We’ve never had an issue with the oysters becoming overcooked and chewy. If desired, you can reduce the bake time to 10 minutes, and then place under the broiler for a minute (just to brown the topping). You should be GREAT! Let us know how it all turns out! And let us know if you have any other questions! All the best, Kris & Wesley
I liked the expert tip
I made this yesterday, for New Years Day. It was perfectly delicious….. I love oysters and this was a wonderful recipe. I’ll be making this for my next dinner party. Thank you for sharing. Happy New Year!
Hi Renee! Yay!! We are so happy you made the oyster casserole and enjoyed it! That’s been a family favorite of ours for many years and we love when other families make it and enjoy it, too! Thank you so much for letting us know and for the wonderful review. We truly appreciate that so very much. Happy New Year! Please stay in touch! xoxo Kris & Wesley
hi guys, what would you serve with this for a summer night in Mobile, Al
It was glorious. I only had 1 lb of oysters, so I added 1 lb of shrimp. It was rich and thick and restaurant quality. My family loved it. We’re from Maryland and owned a home on the Chesapeake Bay, so we enjoy seafood tremendously. A new way of preparing oysters was welcome.
Hi Grammy!! We are SO THRILLED you had such great success with our Oyster Casserole and your addition of shrimp sounds wonderful!! And that’s so awesome that the family loved it, too!! Thank you so very much for letting us know and for the wonderful review! That means the world to us! All the best, Kris & Wesley
This looks so good! I will definitely be trying it this holiday season! My grandma, also from Missouri, used to make a different version of oyster casserole every year! I’ve been making her recipe myself for the last couple years for Thanksgiving. Thank you for sharing your grandma’s recipe!
Hi Christi! That is so awesome! Those Missouri Grandmas know how to make GREAT oyster casseroles, right? Awesome! Have a wonderful Thanksgiving!!! xoxo
Can fresh clams be used instead of oysters
Hi Hal! Sure! It will be a little different in taste, but still delicious. Let us know if you make it and what you think! Best, Kris & Wesley
Merry Christmas from Long Island and Happy New Year
In your directions, it talks about adding cream and Parmesan, but in the ingredients, I see neither. You have whole milk in the ingredients, is that the cream you refer to in the directions?
Hi Steve, thanks so much for bringing this to my attention! I sometimes use heavy cream, and sometimes use milk when I make this dish. I think milk works great, but the cream can give a richer sauce. And oops! Left out the Parmesan in the ingredients. It’s a 1/4 cup. I have updated the recipe to reflect these updates. Thanks again!! All the best, Kris