How to Make It
Preheat oven to 375°F. Sprinkle pecans over bottom of piecrust shell. Whisk together brown sugar, flour, and salt in a large bowl. Add corn syrup, melted butter, eggs, and 3 tablespoons of the liqueur; whisk until smooth. Slowly and gradually pour mixture over pecans, stopping halfway to allow mixture to sink into pecans before pouring in remaining mixture. Loosely cover edges of piecrust with aluminum foil.
Bake in preheated oven 30 minutes. Remove foil. Continue baking until set, about 15 minutes, loosely covering filling with foil during final 10 minutes to prevent excessive browning, if necessary.
Brush pie top evenly with remaining 1 tablespoon liqueur. Let cool completely on a wire rack, about 1 hour. Refrigerate until firm, about 2 hours.