Preheat the oven to 350F. Line the bottom of a 9x13 baking dish with parchment. Lightly grease the parchment.
Add the butter to a small saucepan and melt over medium heat. Add the sugar and stir to dissolve. Add the vanilla and peppermint (if using) and stir to combine. Remove from the heat and let cool slightly.
½ cup unsalted butter, 1 cup granulated sugar, 1 teaspoon vanilla extract, 3 drops peppermint oil
Add the eggs, one at a time, stirring constantly to combine. Stir in the cocoa powder and mix until fully combined. Add the flour and salt and mix thoroughly to combine the batter.
2 large eggs, ½ cup unsweetened cocoa powder, ½ cup all-purpose flour, Pinch of kosher salt
Pour batter into the prepared baking dish. Level the top with a spatula.
Bake for 25-30 minutes or until the top of the brownies is dry and the center is still gooey. Check for doneness by inserting a toothpick into the center.
Gently melt white chocolate and shortening together in a double boiler. Remove from heat before it is completely melted and stir to completely melt it. Pour over brownies, spreading into a thin, even layer. Sprinkle with candy cane pieces.
12 ounces good quality white chocolate, 3 Tablespoons vegetable shortening, 5-6 candy canes
Chill until set, at least 30 minutes
Let cool completely before serving.