Red Lobster's Crab Au Gratin

8 tablespoons (1 stick) butter
1/2 cup onion, minced
2 tablespoons all−purpose flour
1 cup milk, scalded
1/2 teaspoon salt
dash of white pepper
1/4 cup sherry
12 ounce crab meat
1 cup crackers, finely crumbled
1/2 cup cheddar cheese, finely grated

Crumble crackers between waxed paper with a rolling pin.
Reserve just enough crumbs and cheese to top the casserole.
Melt 4 tablespoons of the butter in a large heavy skillet.
Add onion and saut for about 5 minutes or until golden.
Slowly add flour, stirring constantly over low heat.
When flour is blended, gradually add hot milk (scalded) and blend with a whip.
Continue stirring over low heat until the sauce begins to thicken.
Add salt, pepper, and sherry, and continue stirring in a bowl.
Mix crab meat, sauce, and the extra cracker crumbs and cheese.
Place in a lightly greased baking dish.
Sprinkle reserved cracker crumbs and cheese on the top of the casserole.
Dot the top with the remaining 4 tablespoons butter.
Bake uncovered at 350F for about 15 minutes or until the top is golden brown.