Combine butter and cream cheese; cream until smooth. Add flour and salt, mixing well. Shape dough into a ball; chill at least 2 hours.
Roll dough to 1/8-inch thickness on a lightly floured surface. Place in a 9-inch pie plate; trim excess pastry around edges. Fold edge under, and flute. Prick bottom and sides of shell with a fork. Bake at 425° for 12 to 15 minutes or until pastry is golden brown.