Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.

In a large mixing bowl, cream together the unsalted butter, granulated sugar, and brown sugar for 2-3 minutes until light and fluffy.

Add the egg and vanilla extract to the mixture and mix well until fully combined.

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

Gradually add the dry ingredients to the wet mixture and stir gently until just combined.

Fold in the mini chocolate chips.

Cover the dough with plastic wrap and refrigerate for at least 30 minutes.

Scoop portions of dough onto the prepared baking sheet, leaving space between each.

Press half of a marshmallow into the center of each cookie.

Bake for about 12 minutes, monitoring closely.

Drizzle melted semi-sweet chocolate over the warm cookies.

Cool on the baking sheet for a few minutes before transferring to a wire rack.