Hi, Cathy:
This is a recipe that our family has used for many years. I hope it's what you're looking for. We love it on apple salad.

LEMON DRESSING
Makes 1 cup

1/2 c. sugar
1 T. flour
1 egg, slightly beaten
Juice of 1 lemon (Approx. 2 T.)
4 T. butter, melted
1 c. whipped cream (measure AFTER whipping)

Add sugar and flour to egg and mix well. Add lemon juice and pour mixture into melted butter in a heavy small saucepan. Cook over low heat until mixture comes to a boil and is thick. Cool. Fold in whipped cream and chill. This will keep several days in the refrigerator.