Cream the butter and sugars:
In a large mixing bowl, cream together the butter, light brown sugar, and granulated sugar until light and fluffy, about 3 minutes.
Mix in the wet ingredients:
Add the egg and vanilla extract, mixing until just combined. Scrape down the sides of the bowl as needed.
Add the dry ingredients:
Slowly add the flour, baking soda, and fine sea salt. Mix until almost combined, then fold in the dark chocolate chips and crushed candy cane pieces.
Scoop and chill the dough:
Scoop the dough into 2-tablespoon-sized balls and place them on a parchment-lined baking sheet. Chill the cookie dough in the freezer for at least 3-4 hours, or overnight for best flavor.
Bake the cookies:
Preheat the oven to 350°F (180°C). Bake the frozen cookie dough balls, spaced 2 inches apart, for 9-10 minutes. The cookies will appear underbaked when removed but will firm up as they cool.
Decorate and cool:
Press additional candy cane pieces and chocolate chips on top of the cookies while they’re warm. Let the cookies cool completely on a wire rack before serving.
Storage:
Store baked cookies in an airtight container at room temperature for 2-3 days.
Frozen cookie dough can be stored for up to 1 month, though candy cane pieces may start to dissolve over time.