Preheat oven to 350°F (180°C). For the Crust, beat butter in large bowl with electric mixer on medium speed until smooth. Add granulated sugar, egg yolk and salt; beat until well blended. Gradually beat in flour on low speed just until dough begins to clump together. Gather dough into a ball then flatten into a disk. Roll out dough on lightly floured surface to 1/8-inch (3 mm) thickness. Using a small knife, cut out 6 (6-inch/15 cm)) rounds. Lightly spray 6 (4-inch/10 cm) fluted tart pans with removable bottoms with no stick cooking spray. Fit dough rounds in bottom and up sides of tart pans. Refrigerate 30 minutes or until dough is firm.
