1. In a food processor or bowl, combine flour and sugar. Add butter; whirl or rub in with your fingers until fine crumbs form. Add yolk; whirl or mix with a fork until dough holds together. Pat into ball.
2. Divide dough into 6 equal portions. Firmly and evenly press each one over bottom and up sides of a 4 1/2-inch tart pan with removable rim. Set pans slightly apart on a 14- by 17-inch baking sheet.
3. Bake in a 300° regular or convection oven until pale gold, 15 to 25 minutes; let cool at least 15 minutes. If making up to 1 day ahead, cool completely, wrap airtight, and store at room temperature.
Nutritional analysis per crust.