Jumbo Lump Crab Au Gratin

This is a straightforward, restaurant-style crab au gratin you can make at home. It highlights sweet, delicate jumbo lump crab and a creamy, seasoned cheese sauce finished under the broiler for a golden top. The recipe is written so you can follow it step by step, and get reliably impressive results without drama.

I test this in a small cast-iron skillet and in individual ramekins; both work. The key is gentle handling of the crab—treat the lumps with respect—and careful attention to the sauce so it doesn’t curdle when you add the egg and evaporated milk.

Below you’ll find the exact ingredients, the verbatim method to follow, troubleshooting notes, hardware suggestions, and ways to serve it so the dish looks as good as it tastes. Keep the oven timer handy during broiling—this finishes fast.

What’s in the Bowl

This section gives you a clear view of what the sauce and filling are made of before you begin. Read it all once so you know what to prep and what role each part plays.

Ingredients

• ½ cup unsalted butter (1 stick) — fat for sautéing vegetables and building the roux; provides richness without added salt.
• 1 medium onion, finely chopped — base flavor; softens and sweetens the sauce.
• 1 celery rib, finely chopped — aromatic texture and subtle savory note.
• 2 tablespoon green onions, sliced, save some for garnish — mild onion flavor; reserve greens as a fresh finish.
• 1 cloves garlic, minced — a touch of savory depth.
• 2 large egg yolks, slightly beaten — enriches and thickens the sauce when tempered correctly.
• 1 (12-oz.) can evaporated milk — concentrated milk body; contributes creaminess without excess liquid.
• 2 tablespoon all-purpose flour — combines with butter to form a white roux that thickens the sauce.
• Juice of one lemon — brightens the sauce and balances richness.
• 1 teaspoon hot sauce — an undertone of heat to lift the flavor.
• 1 teaspoon Kosher salt — primary seasoning; measure and adjust to taste.
• ½ teaspoon cayenne pepper — concentrated heat; adds warmth without overwhelming.
• ½ teaspoon freshly ground black pepper — sharp, aromatic seasoning.
• ½ cup Gruyere cheese, grated — nutty, melty cheese; use half in the sauce and half on top.
• ½ cup Fontina cheese, grated — creamy melting cheese; split between sauce and topping.
• 1 lb lump crab meat, picked over for shells and cartilage — the star ingredient; handle gently to keep lumps intact.

Jumbo Lump Crab Au Gratin: How It’s Done

1. Preheat the oven to 350°F.
2. Melt ½ cup unsalted butter (1 stick) in a large skillet over medium-high heat.
3. While the butter melts, finely chop 1 medium onion and 1 celery rib, slice 2 tablespoons green onions and reserve some of the green parts for garnish, and mince 1 clove garlic.
4. Add the chopped onion, chopped celery, the white/light-green parts of the sliced green onions, and the minced garlic to the skillet. Cook, stirring, until the vegetables are softened, about 5 minutes.
5. While the vegetables cook, vigorously whisk together 2 large egg yolks (slightly beaten) and the contents of 1 (12-oz.) can evaporated milk in a small bowl until well blended; set aside.
6. Sprinkle 2 tablespoons all-purpose flour over the vegetables and stir to blend thoroughly, cooking about 2 minutes to form a white roux. Do not allow the flour to brown.
7. Using a whisk, add the egg-and-milk mixture to the skillet slowly in a steady stream, whisking constantly to incorporate and prevent curdling.
8. Stir in the juice of one lemon, 1 teaspoon hot sauce, 1 teaspoon Kosher salt, ½ teaspoon cayenne pepper, and ½ teaspoon freshly ground black pepper. Continue to cook and stir for 4–5 minutes, until the sauce thickens to the consistency of a thick creamed soup.
9. Remove the skillet from the heat and fold in half of the grated cheese (use half of the Gruyere and half of the Fontina) until fully melted and incorporated.
10. Pick over 1 lb lump crab meat for shells and cartilage, then gently divide the crab among four mini ovenproof casseroles (or place in one large cast-iron skillet or an 8″x8″ baking dish), taking care not to break up the lump crab.
11. Pour the cheese sauce evenly over the crab, then sprinkle the remaining grated Gruyere and Fontina on top.
12. Bake at 350°F until bubbly, about 15 minutes. Switch the oven to broil and broil until the cheese begins to brown, about 3–5 minutes—watch closely to avoid burning.
13. Remove from the oven, sprinkle with the reserved green parts of the sliced green onions, and serve immediately.

Why You’ll Love This Recipe

The crab is front and center. The sauce supports the crab without hiding it. The cheeses add creaminess and a toasty finish when broiled. Texture is critical here: creamy sauce, soft vegetables, and intact crab lumps create contrast in every bite.

This recipe is practical: it uses pantry-staple items (butter, flour, evaporated milk) and straightforward technique. The most impressive moments are simple—gently folding crab into sauce and watching the top blister and brown under the broiler.

International Equivalents

Au gratin is a technique used in many cuisines—cheese or breadcrumb topping browned under heat. If you want to nod to other traditions, think about swapping one cheese for a local melting variety or adding a hint of smoked seasoning. Keep the method and ratios similar: a white roux, dairy enrichment, and a short bake followed by broil.

Hardware & Gadgets

Essentials

• Large skillet — for the roux and sauce; nonstick or stainless is fine.
• Whisk — prevents curdling when you add the egg-and-milk mixture.
• Mini ovenproof casseroles, cast-iron skillet, or 8″x8″ baking dish — any ovenproof vessel that holds the crab and sauce.
• Box grater — for evenly grated Gruyere and Fontina so they melt smoothly.

Nice-to-have

• Tongs or flexible spatula — for gentle transfer of crab lumps.
• Instant-read thermometer — not necessary, but helpful to check oven consistency if your broiler runs hot.

Things That Go Wrong

Curdled sauce: adding the egg-and-milk mixture too fast or at too high heat will cause curdling. Prevent this by whisking the egg-and-milk into the roux slowly and whisking constantly. Remove the pan from direct high heat if you need to slow down.

Soggy crab: too much liquid or over-stirring the crab will break lumps. Pick over the crab first, then handle gently and pour the sauce over rather than mixing vigorously.

Burned top: broilers vary. Broil only until the cheese just browns—3 minutes can be enough. Stay nearby and watch.

Make It Diet-Friendly

Keep portion sizes small and pair the au gratin with a bright salad or steamed vegetables. To reduce calories or fat, serve the dish in smaller ramekins as an appetizer rather than a main course. Using a reduced portion of the topping cheese will also lower the fat without changing the method.

For sodium control, pick a low-sodium hot sauce and use a bit less Kosher salt, tasting the sauce before you finish. Because the lump crab is the hero, a little trimming of the seasoning still leaves plenty of flavor.

Insider Tips

• Pick the crab carefully. Remove shells and cartilage by hand; nothing ruins the experience quicker than a crunchy surprise.
• Keep the crab lumps large. They look pretty and give texture; fold gently so they stay intact.
• Tempering matters. Add the egg-and-milk slowly and whisk; this prevents scrambled bits and ensures a silky sauce.
• Split your cheese. Melting half into the sauce and sprinkling the rest on top gives both a creamy base and a gratin finish.
• Reserve green onion tops for garnish. They add color and a fresh bite against the rich sauce.

Storage & Reheat Guide

Refrigerate leftovers in an airtight container for up to 2–3 days. The texture of the crab will change slightly after refrigeration, and the sauce will firm up. Reheat gently in a 325°F oven until warmed through, about 10–15 minutes, covering loosely with foil to prevent over-browning. Finish under the broiler briefly if you want to re-crisp the top—watch closely.

Freezing is possible but not ideal: the texture of the crab and sauce will degrade. If you must freeze, use a sturdy freezer-safe container, freeze quickly, and plan to use within one month. Thaw overnight in the refrigerator and reheat as above.

Jumbo Lump Crab Au Gratin FAQs

Q: Can I use canned crab meat? A: This recipe calls for 1 lb lump crab meat picked over for shells and cartilage. If you use canned crab, choose a high-quality lump variety and pick it over the same way. Be gentle when portioning into dishes.

Q: Can I make this ahead? A: You can make the sauce and cool it, then assemble with the crab and refrigerate for a few hours before baking. If you refrigerate assembled dishes, allow them to come closer to room temperature before baking so the center heats evenly.

Q: What if my sauce is too thin? A: Return the skillet to medium-low heat and simmer, stirring, until it thickens. Do not boil. If it’s only slightly thin, a few extra minutes will do the trick.

Q: Can I skip the broiler? A: Yes. Bake until bubbling and the top is lightly golden. The broiler gives the classic browned crust, but a lower, longer bake will still be delicious.

Serve & Enjoy

Serve this straight from the oven with a simple green salad, lemon wedges, and crusty bread for mopping up any extra sauce. For a lighter plate, offer roasted vegetables or steamed asparagus. Garnish with the reserved green onion tops for a fresh contrast.

Eat it hot. The textures are best immediately—the sauce is silky, the cheese on top is golden, and the crab is tender and sweet. This is the sort of dish that feels celebratory but is entirely manageable on a weeknight when you follow the steps. Enjoy.

Jumbo Lump Crab Au Gratin

Rich, cheesy jumbo lump crab au gratin baked until bubbly and browned, finished with sliced green onion for garnish.

Print Recipe Pin Recipe

Prep Time 15 minutes mins

Cook Time 20 minutes mins

Total Time 35 minutes mins

Servings: 8 servings

Ingredients Equipment Method Notes

Ingredients

  

Ingredients

• 1/2 cupunsalted butter1 stick
• 1 mediumonionfinely chopped
• 1 celery ribfinely chopped
• 2 tablespoongreen onionssliced save some for garnish
• 1 clovesgarlicminced
• 2 largeegg yolksslightly beaten
• 112 oz. canevaporated milk
• 2 tablespoonall-purpose flour
• Juice of one lemon
• 1 teaspoonhot sauce
• 1 teaspoonKosher salt
• 1/2 teaspooncayenne pepper
• 1/2 teaspoonfreshly ground black pepper
• 1/2 cupGruyere cheesegrated
• 1/2 cupFontina cheesegrated
• 1 lblump crab meatpicked over for shells and cartilage

Equipment

• Large Skillet
• Whisk
• Oven
• broiler
• mini ovenproof casseroles or 8x8 baking dish

Method

 

Instructions

1. Preheat the oven to 350°F.
2. Melt ½ cup unsalted butter (1 stick) in a large skillet over medium-high heat.
3. While the butter melts, finely chop 1 medium onion and 1 celery rib, slice 2 tablespoons green onions and reserve some of the green parts for garnish, and mince 1 clove garlic.
4. Add the chopped onion, chopped celery, the white/light-green parts of the sliced green onions, and the minced garlic to the skillet. Cook, stirring, until the vegetables are softened, about 5 minutes.
5. While the vegetables cook, vigorously whisk together 2 large egg yolks (slightly beaten) and the contents of 1 (12-oz.) can evaporated milk in a small bowl until well blended; set aside.
6. Sprinkle 2 tablespoons all-purpose flour over the vegetables and stir to blend thoroughly, cooking about 2 minutes to form a white roux. Do not allow the flour to brown.
7. Using a whisk, add the egg-and-milk mixture to the skillet slowly in a steady stream, whisking constantly to incorporate and prevent curdling.
8. Stir in the juice of one lemon, 1 teaspoon hot sauce, 1 teaspoon Kosher salt, ½ teaspoon cayenne pepper, and ½ teaspoon freshly ground black pepper. Continue to cook and stir for 4–5 minutes, until the sauce thickens to the consistency of a thick creamed soup.
9. Remove the skillet from the heat and fold in half of the grated cheese (use half of the Gruyere and half of the Fontina) until fully melted and incorporated.
10. Pick over 1 lb lump crab meat for shells and cartilage, then gently divide the crab among four mini ovenproof casseroles (or place in one large cast-iron skillet or an 8"x8" baking dish), taking care not to break up the lump crab.
11. Pour the cheese sauce evenly over the crab, then sprinkle the remaining grated Gruyere and Fontina on top.
12. Bake at 350°F until bubbly, about 15 minutes. Switch the oven to broil and broil until the cheese begins to brown, about 3–5 minutes—watch closely to avoid burning.
13. Remove from the oven, sprinkle with the reserved green parts of the sliced green onions, and serve immediately.

Notes

Notes
Jumbo lump crab meat can be pricey.  For a more economical version, but still very delicious, we do a combination of jumbo lump and regular crab meat.
Be sure to use a good melting cheese such as fontina, gruyere, Monterrey jack, or even mozzarella.
This au gratin is quite rich.  We serve it as an appetizer with lots of toasted baguette slices.