Toast pecans in dry skillet over medium 3-4 minutes until fragrant; cool and finely chop.
Beat softened butter and ½ cup powdered sugar in large bowl about 3 minutes until light and fluffy.
Mix in bourbon and vanilla thoroughly.
Separately whisk flour, salt, and cinnamon.
Gradually beat flour into butter on low just until combined.
Fold in pecans and brown sugar evenly.
Cover; refrigerate 30 minutes for easier handling.
Heat oven to 350°F; line sheets with parchment.
Roll into 1-inch balls; place 2 inches apart on sheets.
Bake 13-15 minutes until bottoms lightly golden and tops pale.
Cool on sheet 5 minutes; roll warm cookies in powdered sugar.
Once completely cool, roll in powdered sugar again.