I recommend reading this recipe in advance. It's easy, but you need to be prepared for all parts so it goes smoothly.
Line a large baking sheet with parchment paper.
Chop the chocolate bars into 1/2" pieces. They need to be about the same size so that they melt evenly. Do the same with the white chocolate bars, again cutting them into equal sized pieces so they melt evenly.
You'll need a double boiler to melt the chocolates. Or you can use a glass bowl that fits snugly in the top of a saucepan. Just make sure the bottom of the glass bowl will not touch the water that is on the bottom of the pan.
Place one inch of water in the bottom of the double broiler or saucepan. Set the pan over medium heat and allow it to start heating.
Place 2/3 of the semi-sweet chocolate into the top of the double boiler or in the glass bowl. Place the pan or bowl over the steaming water. Make sure that none of the water gets in the chocolate or it will seize up.
Stir the chocolate constantly as it melts. Continue to heat, melt and stir until the temperature of the chocolate reaches 110°–115°F. When the chocolate reaches this temperature, remove it from the heat and immediately stir in the remaining 1/3 of the chocolate. Stir until the mixture is completely smooth.
Pour the melted semi-sweet chocolate onto the prepared pan. Use a rubber spatula to spread the chocolate into a large rectangle. Try to make the chocolate as even as possible, and make it as thin or as thick as you'd like. I ended up with a rectangle that was about 12x15". Shake the pan slightly to even out the chocolate layer.
Repeat the chocolate melting process with the white chocolate. (Clean the pot or bowl quickly if you don't have a second one to use.)
Place 2/3 of the white chocolate into the top of the double boiler or in the glass bowl. Place the pan or bowl over the steaming water.
Stir the white chocolate constantly as it melts. Continue to heat, melt and stir until the temperature of the chocolate reaches 110°–115°F. When the white chocolate reaches this temperature, remove it from the heat and immediately stir in the remaining 1/3 of the white chocolate. Then mix in the peppermint extract. Stir until the mixture is completely smooth.
Allow the white chocolate mixture to sit for about 3 minutes. Then pour it slowly and evenly over the semi-sweet chocolate. (The semi-sweet chocolate should not be set yet. You don't want it to set fully before adding the white chocolate. This will help the layers stick together.)
Use an offset spatula to lightly spread the white chocolate if needed, but I didn't have to do this much since when I poured it, it covered the chocolate nicely. Shake the pan slightly to make a smooth top. Immediately sprinkle the crushed candy canes on top of the white chocolate layer.
Allow the chocolate to set at room temperature. Letting the layers set slowly helps keep the layers from separating. The chocolate should take about 4 hours to set.
Cut the edges off the chocolate, then cut the peppermint bark into squares of the size you'd like.
Notes
Store in an airtight container at room temperature for 3 days. Refrigerate for up to 7 days. This also freezes well for up to 8 weeks.Refer to the article above for more tips and tricks.The calories shown are based on the peppermint bark being cut into 20 pieces, with 1 serving being 1 piece of bark. Since different brands of ingredients have different nutritional information, the calories shown are just an estimate. **We are not dietitians and recommend you seek a nutritionist for exact nutritional information. The information in the nutrition box are calculated through a program and there is room for error. If you need an accurate count, I recommend running the ingredients through your favorite nutrition calculator.**