3 tbsp. (3/8 stick) butter
1/4 c. finely chopped onion
3 tbsp. all-purpose flour
2 c. scalded milk, Half and Half or whipping cream
1/4 tsp. salt
3 white peppercorns
1 sprig parsley
1/4 stalk celery, thinly sliced
Pinch nutmeg

In heavy, non aluminum 2 quart saucepan, melt butter over low heat. Add onion and cook until soft but not browned. Whisk in flour to make roux. Cook, whisking constantly, until roux is frothy and free of lumps, about 2 to 3 minutes. Remove saucepan from heat and slowly add 1/2 hot liquid, whisking constantly. Add remaining liquid and continue whisking until sauce is smooth, about 3 to 5 minutes. Return sauce to medium-low heat and add remaining ingredients. Simmer uncovered, stirring frequently with wooden spoon, until sauce is reduced by about 1/4, about 20 to 30 minutes. Remove from heat and strain. Makes 1 1/2 cups (medium consistency).