You can use whatever chocolate you like - milk, dark, bittersweet, whatever is in the cupboard. I used a 9x13 pan (but I think a larger pan would have yielded thinner pieces of bark in the end) and it made two small boxes of bark.
1 lb chocolate chips
1 lb white chocolate chips
1/2 cup crushed candy cane
Line a pan with parchment paper or waxed paper. Melt the chocolate chips and spread evenly on the lined pan. Let it cool and set (this will go quicker in the refrigerator). Melt the white chocolate chips and add some peppermint extract (a few drops to start, taste it and add more if you want). Spread the melted white chocolate in an even layer over the other chocolate. Sprinkle with the crushed candy cane and press on it a little bit to make the candy cane stick into the white chocolate. Let it all set up and then break it into pieces.