Grease the tart cups and set aside.
In a large bowl, whisk together flour and sugar.
Add butter using a pastry blender. Mix until well combined and butter bits are pea sized. Using a fork, stir in the egg yolk until it is mixed in completely.
Form the pastry dough into a round disk and wrap in plastic wrap. Chill in refrigerator 30 minutes.
Between 2 pieces of parchment paper, roll out pastry dough to a 1/2-inch thickness.
Using a 3-inch round cookie cutter, cut 6 pieces of pastry dough. Place one circle into each tart cup. Lightly press into and up the sides of cup and cut off any extra dough at top edge.
Place the uncooked tart shells onto a rimmed baking pan and chill in refrigerator for 30 minutes.
Preheat oven to 350°F.
Remove pan from refrigerator and prick each tart shell with a fork.
Bake 15 minutes or until tarts start to turn golden in color.
Remove from oven and cool 15 minutes. Slide the point of a knife between the tart pan and the tart shell, lifting up to remove. Place tart shells back onto the rimmed pan until ready to fill with cream.