Butter should be room temp- easy to cream- DO NOT USE MELTED BUTTER !
Cream butter and sugar, Add flour and beaten eggs. Beat on low speed until it is all mixed well. Stir in buttermilk and vanilla. Pour into 2 small pie shells or 1 large shell.
Bake 45-50 minutes at 350 degees. The middle will be set- not wiggly when done- color should be golden brown. I think it tastes even better after it sits in fridge for a day.