In a 3-5 quart dutch oven over medium-low heat, melt 4 tablespoons of butter. Don't allow it to brown. Should take 2-3 minutes.
Then add the flour and stir to form a roux. Allow it to cook for 1 1/2 minutes before it browns. Pour in the seafood stock and sherry, whisk to make a sauce.
Stir in all of the dried spices including the salt then the half and half. Continue stirring until it blends completely. Next, add the pimentos, parsley, and crab meat.
Reduce the heat to low and add the remaining butter, allow it to simmer. Stir frequently being sure to scrape the bottom to loosen any sticking. Cook another 10-15 minutes on very low heat. Turn off the heat and cool for 5-10 minutes. Serve while hot.