Line an 8x8” baking pan with parchment or wax paper leaving enough room around the edge to grab and lift the paper.
In a mixing bowl, mix peanut butter, butter, brown sugar, vanilla and salt. Mix thoroughly until the brown sugar is dissolved. Add powdered sugar and mix.
Press mixture into the parchment lined baking dish, smoothing the top by flattening with the palm of your hand. The flattened mixture should be about ½ inch thick.
Cool in the freezer for about 1 hour, or until firm.
Use a Christmas tree cookie cutter to cut out trees and place them on a tray. Place back in the freezer for about 1 hour, until firm.