01 - Preheat oven to 350°F. Generously grease a 12-cup mini muffin pan with butter or cooking spray.
02 - Combine flour and salt in a mixing bowl. Cut in cold cubed butter using a pastry cutter or fingertips until mixture resembles coarse crumbs. Sprinkle cold water over the mixture, 1 tablespoon at a time, tossing gently with a fork until dough just holds together when pressed.
03 - Roll dough on a lightly floured surface to 1/8-inch thickness. Cut twelve 3-inch circles using a round cutter or glass. Gently press each circle into the wells of the mini muffin tin, extending slightly above the rim.
04 - Whisk brown sugar, corn syrup, melted butter, egg, vanilla, and salt in a medium bowl until completely smooth and well combined. Fold in chopped pecans until evenly distributed.
05 - Divide filling evenly among prepared crusts, approximately 1 tablespoon per mini pie. Bake for 22-25 minutes until filling is set and crusts are golden brown.
06 - Let pies cool in the pan for 10 minutes to set. Carefully run a knife around edges to release, then transfer to a wire rack to cool completely. Serve plain or topped with whipped cream.