Add 2 teaspoons peppermint extract to semi-sweet chocolate and stir until well-combined. Pour chocolate into a 13x9 baking dish and place in the freezer until hardened, approximately 3 minutes.
Remove from microwave and stir until smooth.
Remove from microwave and stir. Return to microwave for approximately 10-20 seconds depending on the wattage of your microwave.
Melt semi-sweet chocolate in a medium glass bowl for 1 minute.
Place waxed paper in a 13x9 baking dish. Leave enough waxed paper along edges to lift peppermint bark from baking dish later.