Line an 8-by-8-inch baking dish with 2 pieces of parchment paper so that the paper hangs over all 4 sides by a couple inches.

Melt the semisweet chocolate chips in a small pot or double boiler. Remove from the heat and add ¼ teaspoon peppermint extract. Stir to combine. Transfer the mixture to the prepared baking dish in an even layer. Immediately melt the white chocolate in a small saucepot or double boiler. You don’t want the semisweet chocolate to set before you add the white chocolate to the top of it. If it sets, the two layers won't stick together. Remove the white chocolate from the heat and add the remaining ¼ teaspoon of peppermint extract. Fold in ¼ cup of the crushed candy canes.

Carefully transfer the white chocolate mixture to the top of the semisweet layer so that it covers the semisweet layer completely. Spread gently with an offset spatula. Sprinkle with remaining crushed candy canes. Add more if you would like (I make sure the entire top is covered with candy cane crumbles).

Set aside at room temperature and allow to set about an hour; do not put it in the refrigerator before it sets. After it sets completely, lift out of the baking dishes and cut or break into bite-size pieces.

Peppermint bark will keep in a tightly sealed container for up to 1 week at room temperature.