From The Modern Family Cookbook

â…” cup sugar
1¼ teaspoons salt
1 tablespoon flour
â…” cup cider vinegar
â…” cup egg yolks, slightly beaten
4 teaspoons prepared mustard
Dash cayenne
¾ cup evaporated milk

Mix sugar, salt and flour in top of double boiler; stir in vinegar and mix until smooth. Cook over direct heat, stirring constantly until mixture boils and thickens. Slowly stir into beaten egg yolks; add mustard and cayenne and return to top of double boiler. Now cook over boiling water for 3 minutes, stirring constantly. Remove from heat and stir in the evaporated milk. Chill before serving. Delicious with fruit salad or head lettuce salad. About 2 cups.
Variation: If preferred, omit the evaporated milk and just before serving, fold in ½ cup whipping cream, whipped until stiff.

My note: You can’t get much more retro than boiled salad dressings. This one also works well as slaw dressing very much like Marzetti’s “Original Slaw Dressing”.