Preheat your oven to 350°F (175°C) and line cookie sheets with parchment paper.

In a large, microwave-safe bowl, combine the butter and 2 cups of semisweet chocolate chips, then microwave and stir in 15-second intervals until fully melted.

Remove the mixture from the microwave and allow it to cool for at least 10 minutes, ensuring it is no longer warm to the touch.

Once cooled, stir in the brown sugar, granulated sugar, beaten eggs and yolk, vanilla extract, and peppermint extract until well combined.

In a separate, medium bowl, whisk together the all-purpose flour, cocoa powder, cornstarch, baking powder, baking soda, and salt.

Gradually incorporate the dry flour mixture into the wet butter-chocolate mixture until completely combined.

If using, stir in the mini chocolate chips.

Drop the cookie dough onto the parchment-lined sheets using a 1 ½ Tablespoon scoop, pressing down slightly to flatten each cookie.

Bake the cookies for 9 minutes, then let them cool on the cookie sheet for 5 minutes before transferring to a wire rack to cool completely.

Prepare the white chocolate by placing it in a medium microwave-safe bowl with vegetable shortening or coconut oil; microwave in 15-second increments, stirring between each, until completely melted.

Dip each completely cooled cookie ⅓ to ½ of the way into the melted white chocolate, place on a wax paper-lined baking sheet, and sprinkle immediately with crushed candy canes. Allow the chocolate to harden before enjoying.