Prep your tools. Line two baking sheets with parchment paper. Preheat your oven to 350°F (175°C).
Have a small zip-top bag and rolling pin ready for crushing candy canes.
Crush the peppermint. Place candy canes in the bag and tap gently until you have a mix of small shards and fine dust. Avoid large chunks that can be too sharp or sticky.
Whisk the dry ingredients. In a medium bowl, whisk together 1 3/4 cups flour, 1/2 cup cocoa powder, 1 teaspoon baking soda, and 1/2 teaspoon salt. Set aside.
Cream the butter and sugars. In a large bowl, beat 3/4 cup unsalted butter with 1/2 cup granulated sugar and 3/4 cup light brown sugar until light and fluffy, about 2–3 minutes. This traps air and helps the cookies bake up soft.
Add eggs and flavorings. Beat in 2 large eggs, one at a time, then mix in 1 teaspoon vanilla extract and 1/4 teaspoon peppermint extract.
Taste the dough after dry ingredients are added and adjust peppermint slightly if needed, but keep it light.
Combine wet and dry. Add the dry mixture to the wet in two additions. Mix on low just until you don’t see dry streaks. Overmixing can make cookies tough.
Fold in the chocolate. Stir in 3/4 cup dark or semisweet chocolate chips and 3/4 cup white chocolate chips.
The mix of both mimics classic peppermint bark layers.
Portion the dough. Scoop the dough into 1 1/2-tablespoon balls (a medium cookie scoop works well). Place on prepared sheets, leaving about 2 inches between each for gentle spread.
Bake. Bake for 9–11 minutes, until edges are set and centers still look slightly soft. They’ll continue to set on the pan.
Do not overbake—chewiness is the goal.
Top with peppermint. As soon as the cookies come out, sprinkle crushed candy canes on top and press lightly so they stick to the warm chocolate. Optionally, add a tiny pinch of flaky sea salt to brighten the flavor.
Cool and set. Let cookies rest on the pan for 5 minutes, then transfer to a wire rack to cool completely. For a fancier look, drizzle melted white chocolate over cooled cookies and add a final dusting of peppermint.