Start with medium hot skillet. Add butter and melt without burning. Add Onion and cook until transparent, do not brown. Add garlic and sauté for 30 seconds. Add heavy cream, Sherry, salt and pepper. Reduce by 1/3 stirring frequently. Add crawfish and cook additional 1 minute to heat crawfish thoroughly, do not over cook which will make Crawfish tough. Add parsley and serve. Makes 1 serving.