Red Lobster Crab au Gratin

8 tbsp butter
1/2 c onion, minced
2 tbsp flour
1 c milk, scalded
1/2 tsp salt
dash white pepper
1/4 c sherry
12 oz crab meat
1 c crackers, crumbled
1/2 c grated cheddar cheese

Save enough crackers and cheese to top casserole. Melt 4 tbsp of butter in large skillet, add onion and cook for 5 minutes or until golden. Add flour, stirring constantly. Gradually add milk and blend with a whip. Stir until thickened. Add salt, pepper and sherry and keep stirring in a bowl. Mix crab, sauce and the extra cracker crumbs and cheese. Put into baking dish. Sprikle reserved cracker crumbs and cheese on top and place remaining 4 tbsp of butter on top of casserole. Bake at 350° for 15 minutes until the top is golden brown