I made the sauce in the afternoon, cooled it to room temp and folded in the cold crabmeat. Then, I put it in my mom's adorable shell shaped gratin dishes and tpped it with cheese-there was easily enough for 6. I Put the dishes in a roasting pan, covered it, and refrigerated until dinner time. It took longer to cook since it started cold, but it was super easy.
1 lb lump crabmeat (I used the homogenized kind)
1/4 cup butter
1 medium onion, chopped
1 large celery stalk, chopped
1 small green pepper, chopped (I used a Hungarian pepper for its mild flavor and heat, but next time i'll use red bell pepper)
2 medium garlic cloves, minced
4 green onions, chopped
1/4 cup flour
2 cups milk
1/4 cup dry bread crumbs
1 tsp salt
1/4 tsp cayenne (I used emeril's essence)
1/4 tsp freshly ground black pepper
2 egg yolks, beaten (I added this.)
Juice of 1-2 lemons
3/4 cup shredded cheddar cheese (next time I'll use parmigiano-reggiano)
Grease a 13x9 baking dish or 6 gratin dishes. Pick through the crab, disgarding bone or cartilage, but don't break up the lumps.
Melt butter in a 12" skillet and add all the veg, sauteing until onion is translucent. Add the flour and cook, stirring 3 minutes ( don't let it brown). Add milk slowly, stirring constanly, and bring to a boil. Add bread crumbs and seasonings, stirring. Add a 1/2 cup os hot sauce by big spoonfuls to egg yolks, stirring constanly, and then add egg yolk mixture back to sauce. Let cook another 3 minutes, stirring.
Add the lemon juice to taste. Taste and correct seasonings.
Put into greased dishes and top with cheese. Bake 15-20 minutes or until golden brown and bubbly.
Serve with hot french bread.