Transform your dinner table into a French bistro with this luxurious Shrimp and Crab au Gratin! This indulgent seafood casserole combines tender crab meat and succulent shrimp in a rich, creamy Mornay sauce, all topped with golden melted cheese. Despite its elegant French name, this dish is simply a sophisticated comfort food casserole that brings restaurant-quality flavors to your home kitchen. Perfect for impressing guests or treating your family to something extraordinary.
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Why this recipe works
The secret lies in the classic Mornay sauce, a rich cheese sauce built on a blonde roux foundation. This technique creates a silky base that perfectly coats the seafood without overpowering its delicate flavors. The double layer of cheese (melted into the sauce and baked on top) provides both creaminess and that coveted golden-brown finish that makes au gratin dishes so appealing.
Crab and Shrimp au gratin Recipe Ingredients
For this seafood au gratin recipe, you’ll need:
- Unsalted butter – Creates the roux base and adds richness to the sauce
- Celery – Provides aromatic foundation and subtle crunch
- White onion – Adds sweet depth and classic mirepoix flavor
- All-purpose flour – Thickens the sauce and prevents separation
- Salt – Enhances all flavors and balances the richness
- Finely ground black pepper – Adds warmth without overwhelming seafood
- American cheese, cubed – Melts smoothly for a creamy sauce consistency
- Whole milk – Creates the liquid base for the Mornay sauce
- Crab meat – Provides sweet, delicate seafood flavor
- Shrimp, cooked – Adds meaty texture and classic seafood taste
- Tabasco sauce – Gives subtle heat that enhances seafood flavors
- Cheddar cheese, shredded – Creates the golden, bubbly top layer
How to Make Baked Shrimp and Crab au Gratin
To prepare the Mornay sauce:
- Put the unsalted butter in a saucepan over medium-low heat.
- While the butter is melting, finely mince the celery and onion. Reserve both for later.
- When the butter stops foaming, add the minced celery and onion to the saucepan. Stir the veggies and sauté for about a minute until they soften.
- Sprinkle the flour into the saucepan and stir well to coat the flour in butter. Cook for a couple of minutes until the flour darkens to a pale blond color and there is a strong aroma of freshly baked pie crust.
- Whisk in the milk and Tabasco sauce. Continue to whisk until the sauce thickens slightly.
- Add the American cheese and stir with a spoon until it melts.
- Remove the saucepan from the heat and stir in the crab meat and shrimp.
To bake the seafood au gratin:
- Preheat the oven to 350°F.
- Lightly grease a gratin or a casserole dish and pour in the Mornay sauce with seafood.
- Top the seafood mixture with the shredded cheddar cheese.
- Bake for 20 minutes. If the top still isn’t golden brown, finish it under the broiler.
As an alternative, use ramekins for individual servings.
Crab and Shrimp au Gratin Recipe Variations
You can use the same general directions and replace the shrimp and crab meat with other ingredients.
Besides the classic sole au gratin, try scallops or lobster.
Add some chopped shallots to go along with the celery and onions.
Bump up the cheese flavor with sharp cheddar cheese.
Give it a little kick of heat with a dash of cayenne pepper or hot sauce.
Add a layer of bread crumbs on top of the shredded cheese for a crunchier crust.
If you are after a more authentic taste, try replacing the American and cheddar cheese with Gruyère. Swiss, Fontina, and Parmesan are also good options.
What to Serve Seafood au Gratin With
Enjoy this Shrimp and Crab au Gratin recipe as a main course or an appetizer. When serving it as a starter, the best way to eat it is on toasted bread rounds. To turn the gratin into a main course, try adding one or more of these components to the meal:
- White rice. Spoon a large portion of the casserole directly over a mound of white rice for a casual and filling dinner in a bowl. This is an excellent option for buffets or game-day dining.
- Steamed vegetables. Some veggies like carrots, broccoli, and cauliflower on the side go a long way to help lighten up this rather heavy casserole. Since the seafood au gratin is so flavorful, season the vegetable with only a bit of salt and pepper, and skip the butter.
- Roasted potatoes. For a tasty way to add bulk to your seafood casserole without a lot of hassle, make some roasted red potatoes.
- Wine. A crisp and dry white wine pairs wonderfully with this seafood dish. Chardonnay, Pinot Grigio, or Sauvignon Blanc are great choices.
Storage & reheating instructions
- Refrigerator Storage: Store covered in refrigerator for 2-3 days. Please note that the texture of seafood may become slightly mealy over time.
- Reheating Method: Reheat gently in a 300°F oven for 15-20 minutes until warmed through. Add a splash of milk if the sauce appears too thick.
- Freezing: Not recommended, as dairy-based seafood dishes don’t freeze well, and the texture will suffer.
Favorite Shrimp and Crab Recipes
- Crab Bisque
- Imitation Crab Salad
- Killer Shrimp
- Maryland Crab Cakes
- Shrimp Alfredo
- Shrimp and Grits
- Shrimp Casserole
- Shrimp Remoulade
- Tempura Shrimp
More Au Gratin Recipes
Find lots of easy casserole recipes and the best seafood recipes on CopyKat!
Many thanks go to Bill Spalding for this recipe.
Shrimp and Crab au Gratin Easy Copycat Recipe
Ingredients
- 4 tablespoons butter
- 1/2 cup finely diced celery
- 1/2 cup finely diced white onion
- 4 tablespoons all-purpose flour
- 1/2 teaspoon salt
- 1/2 teaspoon finely ground black pepper
- 5 ounces American cheese cubed
- 1/2 teaspoon salt
- 2 cups milk
- 1/2 teaspoon Tabasco sauce
- 1/4 pound cooked crab meat
- 1/2 pound cooked shrimp
- 1 cup shredded cheddar cheese
- 3 cups cooked rice to serve
Instructions
- Preheat the oven to 350°F.
- Melt the butter in a medium-sized saucepan over medium-low heat. Add the celery and onion and cook, stirring occasionally, until the onions are translucent.
- Add the flour, stir to incorporate, and cook for about 2 minutes or until fragrant. Add the milk and stir constantly until thickened. Add the cubed American cheese and stir until melted. Then add the crab and shrimp.
- Pour the mixture into a greased 1 1/2–quart casserole dish and top with shredded cheese. Bake for 20 minutes and serve over hot cooked rice.
We loved this around my house.
Very poor recipe if you must use any kind of “pasturized cheese spread” when preparing a high quality gourmet cheese sauce is infinitely preferable both in quality and flavor.
C. Holliday
So you made the recipe and it was bad? Or you just don’t like the ingredients? Processed cheese has its places in life, they are limited, but sometimes they are perfect for *some* recipes