Preheat oven to 350° F. Line three baking sheets with parchment paper.
Combine the chopped bittersweet chocolate with the butter in a large stainless steel bowl or double boiler over simmering water. Stir frequently until melted and smooth. Remove from heat and set aside. Continue to heat the simmering water.
Whisk flour, baking powder, and salt together in a small bowl. Set aside.
In another large heat-proof bowl, whisk eggs, sugar, and vanilla together. Set the bowl over the simmering water and stir constantly until the sugar dissolves and the mixture is just warm to the touch.
Stir the egg mixture into the warm (not hot) chocolate.
Stir in the flour mixture until just combined before folding in ½ cup of the crushed candy canes and the chocolate chips.
Drop rounded tablespoons of batter at least 1 1/2 inches apart on prepared baking sheets.
Bake until the surface of the cookies looks glossy and set but the centers are still gooey, about 12 minutes.
Place baking sheets on racks and immediately sprinkle the tops with the remaining peppermint candy. Cool the cookies completely on the baking sheets.