Fit piecrust into a 9-inch pieplate according to package directions; fold edges under and crimp.
Bake at 425° for 7 minutes or until lightly browned; cool.
Combine nectar and next 5 ingredients in a medium saucepan. Bring to a boil over medium heat, whisking constantly; boil, whisking constantly, 1 minute or until mixture thickens. Remove from heat.
Stir in butter and vanilla. Cover tightly with plastic wrap, and cool to room temperature. Spoon mixture into prepared piecrust; cover and chill 8 hours. Garnish, if desired.