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Shrimp au gratin is a Louisiana-style baked dish of tender shrimp in a creamy, sharp cheese sauce with onion, bell pepper, and a little cayenne heat, finished with a golden, bubbly top. This home version is inspired by the Ralph & Kacoo’s classic. It takes about 50 minutes from start to finish and serves four.
What Makes Ralph & Kacoo’s Shrimp Au Gratin Worth Recreating?
Ralph & Kacoo’s is a well-known Louisiana seafood restaurant, and shrimp au gratin is the kind of Gulf Coast comfort dish people crave when they can’t get to a table. The appeal is the contrast: sweet, snappy shrimp in a rich, silky sauce under a browned, cheesy crust.
The flavor sits somewhere between a cheese sauce and a Creole-leaning béchamel. You get the savory base of onion and bell pepper, a gentle cayenne warmth, and a touch of lemon to keep it from feeling heavy.
One note on honesty: I don’t have the restaurant’s official recipe, and I won’t pretend to. This is a technique-driven version built from how shrimp au gratin is classically made, and it is easy enough for a weeknight.
Ingredients
- 1 1/2 lb large shrimp, 21-25 count (peeled and deveined, tails removed)
- 4 tbsp unsalted butter, divided
- 1/2 cup finely diced yellow onion
- 1/4 cup finely diced green bell pepper
- 2 cloves garlic, minced
- 1/4 cup all-purpose flour
- 1 1/2 cups whole milk (warmed in the microwave for 60 seconds)
- 1/2 cup heavy cream (or use all milk for a lighter sauce)
- 6 oz sharp cheddar, freshly shredded, about 1 1/2 cups
- 4 oz Monterey Jack, freshly shredded, about 1 cup (or Colby Jack)
- 1 tsp Creole seasoning (choose a low-salt blend if you can)
- 1/2 tsp sweet Hungarian paprika (adds color and gentle sweetness)
- 1/4 tsp cayenne pepper (reduce to a pinch for mild)
- 1/2 tsp kosher salt (adjust to taste at the end)
- 1 tsp Worcestershire sauce
- 2 tsp fresh lemon juice
- 3 tbsp sliced green onions (the green parts only)
- 1/2 cup panko breadcrumbs
- 1/4 cup grated Parmesan
- 2 tbsp unsalted butter, melted (for the topping)
How to Make Shrimp Au Gratin
Step 1: Prep the Shrimp and Oven
Heat the oven to 400°F (200°C) and butter a 2-quart baking dish. Pat the shrimp very dry with paper towels, then season with 1/2 tsp of the Creole seasoning.
Melt 1 tbsp butter in a large skillet over medium-high heat. Sear the shrimp for about 1 minute per side, until just pink at the edges but still translucent in the center. Move them to a plate, since they will finish cooking in the oven.
Step 2: Build the Vegetable Base and Roux
In the same skillet, melt the remaining 3 tbsp butter over medium heat. Cook the onion and bell pepper for 4 to 5 minutes, until soft and translucent but not browned.
Add the garlic and cook for 30 seconds, then sprinkle in the flour. Stir constantly for 2 minutes until the paste smells nutty and looks pale blond.
Step 3: Make the Cheese Sauce
Pour in the warm milk about 1/2 cup at a time, whisking well after each addition so no lumps form. Add the cream and simmer gently for 3 to 4 minutes, until the sauce coats the back of a spoon.
Take the pan off the heat. Stir in all the Monterey Jack and 1 cup of the cheddar, then add the remaining Creole seasoning, paprika, cayenne, salt, Worcestershire, and lemon juice. Taste and adjust the salt.
Step 4: Assemble the Gratin
Fold the shrimp and any juices from the plate into the sauce, along with the green onions. Scrape everything into the baking dish and spread it level.
Toss the panko, Parmesan, remaining 1/2 cup cheddar, and melted butter in a bowl. Scatter this evenly over the top.
Step 5: Bake Until Bubbly and Golden
Bake for 12 to 15 minutes, until the sauce bubbles at the edges and the shrimp are opaque and curled into a loose “C.” If the top needs more color, broil for 1 to 2 minutes, watching closely.
Rest the dish for 5 minutes. The sauce thickens as it cools slightly, so it spoons neatly instead of running.
How Close Is This to the Ralph & Kacoo’s Version?
It matches the overall character: shrimp in a cheesy, Cajun-seasoned cream sauce with a baked, browned top. I can’t confirm the restaurant’s exact cheese blend, seasoning, or proportions, so treat this as a faithful style match rather than a verified clone.
To get closer to your own memory of the dish, adjust three things: cheese sharpness (more cheddar for tang, more Jack for creaminess), cayenne level, and how much sauce surrounds the shrimp. The paprika is my own Hungarian touch and you can leave it out.
Is There an Easier Version?
Yes, you can streamline this to one pan and about 35 minutes with a few shortcuts.
- Skip the pre-sear and stir raw, dry shrimp straight into the sauce. Bake 15 to 18 minutes instead.
- Use a pre-diced onion and pepper blend, often sold as “holy trinity” mix when you add celery.
- Top with crushed buttery crackers instead of the panko mixture.
The trade-off is slightly less browned flavor in the shrimp, but the dish is still creamy and satisfying.
Can You Make It Ahead?
You can make the sauce up to 2 days ahead and refrigerate it, but assemble with the shrimp right before baking. Cooked shrimp sitting in sauce overnight turn tough and rubbery.
Reheat the sauce gently with a splash of milk until pourable, fold in the seared shrimp, add the topping, and bake. Leftover baked gratin keeps for 2 days in the fridge. Reheat covered at 325°F (160°C) for 10 to 15 minutes to protect the shrimp.
Can You Use Frozen Shrimp?
Yes, and in many kitchens frozen is the more practical choice. Most shrimp sold “fresh” at the counter was previously frozen anyway.
Thaw them in a bowl of cold water for 15 to 20 minutes, then pat thoroughly dry. Wet shrimp release water into the sauce and thin it out. If you’re buying fresh, ask your fishmonger which Gulf or domestic shrimp are in season, since that usually means better flavor and fair pricing.
What Should You Serve With It?
Serve it over steamed white rice or with toasted French bread to catch the sauce. A crisp green salad with a lemony vinaigrette or sautéed green beans cuts through the richness.
Ingredients
- 1 1/2 lb large shrimp, 21-25 count peeled and deveined, tails removed
- 4 tbsp unsalted butter, divided
- 1/2 cup finely diced yellow onion
- 1/4 cup finely diced green bell pepper
- 2 clove garlic, minced
- 1/4 cup all-purpose flour
- 1 1/2 cup whole milk warmed in the microwave for 60 seconds
- 1/2 cup heavy cream or use all milk for a lighter sauce
- 6 oz sharp cheddar, freshly shredded, about 1 1/2 cups
- 4 oz Monterey Jack, freshly shredded, about 1 cup or Colby Jack
- 1 tsp Creole seasoning choose a low-salt blend if you can
- 1/2 tsp sweet Hungarian paprika adds color and gentle sweetness
- 1/4 tsp cayenne pepper reduce to a pinch for mild
- 1/2 tsp kosher salt adjust to taste at the end
- 1 tsp Worcestershire sauce
- 2 tsp fresh lemon juice
- 3 tbsp sliced green onions the green parts only
- 1/2 cup panko breadcrumbs
- 1/4 cup grated Parmesan
- 2 tbsp unsalted butter, melted for the topping
Instructions
Step 1: Prep the Shrimp and Oven
- Heat the oven to 400°F (200°C) and butter a 2-quart baking dish. Pat the shrimp very dry with paper towels, then season with 1/2 tsp of the Creole seasoning. Melt 1 tbsp butter in a large skillet over medium-high heat. Sear the shrimp for about 1 minute per side, until just pink at the edges but still translucent in the center. Move them to a plate, since they will finish cooking in the oven.
Step 2: Build the Vegetable Base and Roux
- In the same skillet, melt the remaining 3 tbsp butter over medium heat. Cook the onion and bell pepper for 4 to 5 minutes, until soft and translucent but not browned. Add the garlic and cook for 30 seconds, then sprinkle in the flour. Stir constantly for 2 minutes until the paste smells nutty and looks pale blond.
Step 3: Make the Cheese Sauce
- Pour in the warm milk about 1/2 cup at a time, whisking well after each addition so no lumps form. Add the cream and simmer gently for 3 to 4 minutes, until the sauce coats the back of a spoon. Take the pan off the heat. Stir in all the Monterey Jack and 1 cup of the cheddar, then add the remaining Creole seasoning, paprika, cayenne, salt, Worcestershire, and lemon juice. Taste and adjust the salt.
Step 4: Assemble the Gratin
- Fold the shrimp and any juices from the plate into the sauce, along with the green onions. Scrape everything into the baking dish and spread it level. Toss the panko, Parmesan, remaining 1/2 cup cheddar, and melted butter in a bowl. Scatter this evenly over the top.
Step 5: Bake Until Bubbly and Golden
- Bake for 12 to 15 minutes, until the sauce bubbles at the edges and the shrimp are opaque and curled into a loose "C." If the top needs more color, broil for 1 to 2 minutes, watching closely. Rest the dish for 5 minutes. The sauce thickens as it cools slightly, so it spoons neatly instead of running.
As a dietitian, I like pairing it with something fibrous and bright. The shrimp provide lean protein, while the cheese and cream add saturated fat and sodium. Using all milk in place of cream, and cutting the topping cheese slightly, lightens it without losing the gratin character.
More Copycat Recipes to Try
- Rakott Krumpli Recipe – Hungarian Chef
- Paprikash Recipe Authentic – Hungarian Chef
- Stuffed Cabbage Hungarian Recipe – Hungarian Chef
Rebecca Novak is a trained chef with over 10 years of experience in the food industry. She has worked in both fine dining and casual Hungarian restaurants and specializes in creating dishes using fresh, seasonal ingredients. She also loves exploring different cuisines worldwide, which allows her to bring unique flavors and ideas to the recipes she creates for Hungarianchef.com. Read more