Preheat oven to 350 degrees F. Line cookie sheets with greased foil, shiny side up.
In a small saucepan, combine brown sugar, butter, and syrup. Cook and stir over medium heat until well blended. Remove from heat.
Stir in the nuts, flour, and liqueur. Mix until well blended.
Drop teaspoonfuls onto a greased, foil-lined cookie sheet about 5 inches apart (bake only 4-5 at a time; cookies spread when baked). Bake for 9-11 minutes; let stand 1 minute.
Remove from cookie sheet. Pull up three sides to center to form a triangle, or roll around the greased handle of a wooden spoon. If cookies are difficult to remove from sheet, reheat them in oven about 30 seconds. Cool on rack.