You will need:

1 cup butter
¼ c celery finely diced
¼ c onion finely diced
½ c flour
Add 1 qt whole milk
Add l lb crabmeat
1 to 2 T parsley
Pepper to taste
Old bay to taste
Dry sherry

Melt butter in dutch oven or equivalent, Cook butter, celery and onion on medium heat until celery and onions are translucent
Slow add about ½ c flour slowly to mixture until well incorporated
Slowly add 1 c heavy cream stirring into mixture then add milk, crab, parsley, pepper, old bay and sherry.
Simmer on Low for 1 hour. (I did 45 minutes) Stir as necessary

Enjoy!