In the bowl of an electric mixer fitted with the paddle attachment, blend the cream cheese and softened butter until smooth and thoroughly blended. Add the flour and stir until just combined; do not overmix. Transfer the dough to a piece of plastic wrap and wrap tightly. Refrigerate for 1 hour, or until thoroughly chilled.

Preheat the oven to 325 degrees F.

When the dough has chilled, remove it from the refrigerator and divide it into 24 even portions. Roll the dough into smooth balls; they should be about 1-inch in diameter. Transfer the dough portions to the wells of a mini-muffin pan. Using your fingers, press the dough onto the bottom and all the way up the sides of the wells.

In a small bowl, beat the egg together with the brown sugar, melted butter, whiskey, vanilla, and salt.

Divide the pecan pieces evenly among the wells of the muffin tin, then spoon the egg mixture over the nuts, dividing it evenly between the wells.

Bake the pies until the pastry is golden brown and the filling is set, 25 to 30 minutes. Set aside on a cooling rack, then carefully remove the mini pies from the pan and allow to cool completely before storing in airtight tins.