Line an 8" baking pan with aluminum foil, allowing foil to come up along the sides of the pan. Smooth out any wrinkles and set aside.

In a medium saucepan over low-medium heat, melt the semi-sweet chocolate, stirring constantly, until smooth. You may also do this in the microwave, melting chocolate in 15 second intervals and stirring thoroughly with a spatula between each interval. Once chocolate is completely melted, stir in peppermint extract.

Pour melted semi-sweet chocolate into prepared baking pan, spreading with a spatula into an even layer (it will be very thin-- this is ok). Rap pan on counter top several times to settle chocolate and remove any air bubbles. Crush 2/3 cup of the pretzels into medium-size pieces and sprinkle over wet chocolate. Place pan in the refrigerator or freezer for 20 minutes or until completely set.

After you are sure semi-sweet chocolate layer is completely set, move onto the white chocolate layer. In a medium saucepan over low-medium heat, melt the white chocolate, stirring constantly, until smooth. You may also do this in the microwave, melting chocolate in 15 second intervals and stirring thoroughly with a spatula between each interval.

Pour melted white chocolate directly on top of semi-sweet layer, gently spreading with a spatula into an even layer. The pretzels will make it slightly difficult to spread but do the best you can. Be careful not to disturb the semi-sweet layer on the bottom, as it will melt a bit once the hot white chocolate hits it. Rap pan on counter top several times to settle chocolate and remove any air bubbles.

Crush the remaining 1/3 cup of pretzels into small pieces. Sprinkle crushed pretzels and crushed candy canes on top and tap pan on counter again to settle everything. Place pan in the refrigerator or freezer until completely set.

Once entire pan is completely hardened, remove bark from the pan and peel off the foil. Break into desired size pieces or cut squares. If you choose to cut into squares, allow pan to sit at room temperature for about 10 minutes, then cut using a very sharp knife. Bark should be stored in the refrigerator and will keep for up to 3 weeks.