Spray a 9x13 baking pan with baking spray and line with parchment paper, so that there is overhang on both sides (for easy lifting). The baking spray is optional, but helps the paper stick better.
In a double boiler (bowl placed over a pot of steaming water), melt the semi-sweet chocolate chips stirring constantly. This can also be done in a microwave.
Once melted, remove from heat and slowly stir in half of the peppermint extract (¾ tsp).
Pour melted chocolate into baking pan and spread evenly with an offset spatula.
Place pan in refrigerator for 10 minutes or until set.
In a double boiler, melt the white chocolate chips stirring constantly.
Once melted, remove from heat and slowly stir in the remainder of the peppermint extract (¾ tsp).
Remove pan from refrigerator.
Pour melted white chocolate on top of semi-sweet chocolate and spread evenly with an offset spatula.
Sprinkle Peppermint Bits all over top of white chocolate and press down gently with your hand to ensure they stick.
Let sit at room temperature for about an hour.
Once set, pull bark out of pan and break into pieces with your hands or cut into uniform shapes with a knife.
Store in an airtight container at room temperature.