Line an 8×8 or 9×9 pan with parchment and lightly spray for easy release.
Melt semi-sweet chocolate chips with half the condensed milk until smooth.
Spread the chocolate mixture in the pan and chill 10 minutes.
Melt white chocolate with the remaining condensed milk, then stir in peppermint and a little red coloring.
Pour the peppermint layer over the chocolate and gently swirl for a marbled look.
Sprinkle crushed candy canes on top and press lightly.
Chill at least 4 hours or overnight until fully set.
Lift out, slice into squares, and wipe the knife between cuts for clean edges.