How to Make It
Make the dough: Combine flour, cream cheese, butter, and fine salt in a stand mixer fitted with the paddle attachment. Beat on medium-low speed until a moist, crumbly dough forms, about 30 seconds.
Divide dough into 24 pieces; roll into balls. Press each ball into bottoms and up sides of the cups of a mini muffin pan, making sure dough comes up a little over the edges of the cups. Cover with plastic wrap, and freeze until firm, about 15 minutes. Preheat oven to 350°F.
Make the filling: Whisk together brown sugar and flour in a 2- or 4-cup liquid measuring cup with a spout (or similar spouted container). Add bourbon, egg, melted butter, vanilla, and fine salt; whisk to combine. Divide chopped pecans evenly among dough cups. Pour filling evenly into cups. Top each with a pecan half.
Bake in preheated oven until crusts are golden brown, 30 to 35 minutes. While tassies are still warm, invert pan onto a wire rack to release tassies. Turn them right side up, and let cool completely. Top with flaky salt, if desired. (Tassies can be stored in an airtight container in refrigerator up to 4 days or in freezer up to 3 months.)