Preheat the oven to 350° F.
Spray a 9″ square baking dish with cooking oil spray, and dust with flour.
Melt unsweetened chocolate and butter in a double boiler, stirring frequently until smooth.
Cool to room temperature.
While the chocolate is cooling, in a large bowl, beat eggs, sugar, vanilla, and peppermint extract until well combined.
Beat in the chocolate mixture.
Slowly, stir in flour.
Pour the batter into a greased pan.
Bake in the oven for 45 minutes.
Test the peppermint brownies with a toothpick for doneness.
Arrange mint chocolate squares on top of brownies.
Return to oven for just a minute or two, until mint squares are soft/melted.
Use a spatula to spread mint squares across all brownies.
Sprinkle crushed candy canes on top.
Allow the peppermint brownies to cool before cutting and serving.