Preheat the oven to 350°F (175°C) and grease a baking dish.
In a large bowl, combine melted butter, granulated sugar, and brown sugar.
Add in hot chocolate mix and cocoa powder; mix until fully incorporated.
Beat in the eggs and vanilla extract until the batter is smooth.
In another bowl, whisk together flour, baking powder, and salt.
Gradually add the dry ingredients to the wet ingredients and mix until just combined.
Fold in the peppermint chocolate chips or candy canes.
Spread the batter evenly in the prepared baking dish.
Bake for 25-30 minutes or until a toothpick comes out clean when inserted in the center.
Allow to cool before slicing into squares and serving.