Preheat oven to 350 degrees F. Line a baking sheet with parchment paper or Silpat baking mat or parchment paper. Set aside.
In a medium bowl, whisk together flour, baking soda, sea salt, and cocoa. Set aside.
With a mixer, cream butter and sugars together until smooth. Add in eggs, one at a time. Next, add in vanilla extract and mix until combined.
Gradually add flour mixture and beat until just combined. Stir in the chocolate chunks or chips. Scoop the dough into rounded tablespoons and place on prepared baking sheet, about 2 inches apart. Bake cookies for 10 minutes, or until cookies are set, but still soft in the center. Don't overbake. Remove from oven and let sit on baking sheet for 3 minutes. Move to a cooling rack and cool completely.
While the cookies are cooling, make the ganache. Add the chocolate to a large bowl. Heat the cream in a small saucepan over medium heat just until it bubbles around the edges. Remove the cream from the heat and pour it over the chocolate. Let the mixture stand for 30-45 seconds, then stir until the chocolate melts and a smooth ganache comes together, about 1-2 minutes.
Lay out a large sheet of parchment paper or wax paper. Dip the cookies, halfway, into the warm ganache. Place the dipped cookies on paper. Sprinkle with candy cane pieces. Let cookies sit until ganache hardens, about 2 hours. To speed up the process, you can place the cookies in the refrigerator to chill.
Note-store cookies in an airtight container for up to 4 days.