1 pound chopped bittersweet chocolate
1 pound chopped white chocolate
8 drops peppermint oil
3/4 cup chopped candy canes
Line an 11 x 17-inch baking sheet with parchment paper. Adjust amounts for different sized cookie sheets. Set aside.
Melt bittersweet chocolate in a heavy pot on low heat, stirring constantly. Stir in 4 drops peppermint oil or more to taste.
Spread chocolate evenly onto the prepared pan. Chill until set, about 1 hour.
Melt white chocolate in a heavy pot on low heat, stirring constantly. Stir in remaining four drops of peppermint oil, then add candy canes.
Spread white chocolate mixture over chilled dark chocolate, spreading to the edge of the pan. Chill until set. Break into pieces and serve.