Preheat your oven to 375°F (190°C) and line two baking sheets with parchment paper.

In a microwave-safe bowl, combine chopped semi-sweet baking chocolate and unsalted butter. Heat in 30-second intervals until smooth.

In a mixing bowl, whisk together all-purpose flour, baking powder, salt, and Dutch-process cocoa powder.

In a stand mixer, beat together large eggs, light brown sugar, vanilla extract, and peppermint extract until light and frothy.

Add the slightly cooled melted chocolate and butter mixture to the wet ingredients and mix on low.

Gradually add the dry ingredient mixture to the wet ingredients, mixing until just combined.

Fold in the semisweet chocolate chunks until evenly distributed.

Cover the cookie dough with plastic wrap and chill in the refrigerator for at least 30 minutes.

Use a cookie scoop to portion out dough onto the prepared baking sheets, spacing them about 2 inches apart.

Bake in the preheated oven for approximately 9 minutes.

Top each cookie with half of a large marshmallow and return to the oven for an additional 2-3 minutes.

Allow the cookies to cool on a wire rack, then drizzle with chocolate and sprinkle crushed peppermint candies on top.