Preheat the oven to 350 degrees F.

Line two baking sheets with parchment paper.

In a large bowl or a bowl of a stand mixer, beat the butter, granulated sugar, and brown sugar until creamy, about 2 minutes.

Add the egg and vanilla extract, and beat until combined.

Add the baking soda, salt, and cocoa powder, and mix until combined.

Stir in the flour, followed by 1 cup of chocolate chips.

Roll the cookie dough into dough balls and place on prepared baking sheet. I fit 6 on each baking sheet.

Bake in the preheated oven for 8 minutes.

After 8 minutes, press ½ of a large marshmallow into the center of each cookie. Bake for another 3 minutes.

Let cool for about 5 minutes and then transfer to a cooling rack to cool completely.

Melt the remaining chocolate chips in a microwave safe bowl in intervals of 30 seconds.

Drizzle over the baked cookies and then top with sprinkles, if desired.

Enjoy!