Prepare the Dough:

• Preheat your oven to 350°F (175°C). Line baking sheets with parchment paper.
• In a microwave-safe bowl, melt the butter and 1½ cups of chocolate chips in 20-second increments, stirring until smooth.
• Stir in the brown sugar until fully combined.
• Add the eggs one at a time, mixing well after each addition. Stir in the peppermint extract.
• In a separate bowl, whisk together the cocoa powder, baking soda, and flour. Gradually add the dry ingredients to the wet ingredients, mixing until a soft dough forms.
• Fold in the remaining 1 cup of chocolate chips.

Shape and Bake:

• Scoop tablespoon-sized balls of dough and place them 2 inches apart on the prepared baking sheets.
• Bake for 8–10 minutes, or until the edges are set but the centers are still soft.

Add the Marshmallows:

• Remove the cookies from the oven and immediately press a halved marshmallow onto the center of each cookie.
• Return the cookies to the oven for 2 minutes, or until the marshmallows puff slightly.

Decorate:

• Press a small chocolate square onto the marshmallow of each cookie while they’re still warm.
• Sprinkle the cookies with crushed candy canes or peppermint candies.

Cool and Serve:

• Let the cookies cool on the baking sheet for 5 minutes, then transfer them to a wire rack to cool completely.
• Serve warm for a gooey, melty treat, or store in an airtight container for up to 3 days.