To make the hot chocolate cookie dough, take the flour, baking soda, cocoa powder, and cornstarch in a bowl. Mix well. Now, add the softened butter, granulated sugar, vanilla extract, egg, milk, and chocolate chips to the batter and combine using a wooden spoon to make a thick cookie dough. (See the video for a visual)Cover and freeze the cookie dough for 20 minutes or refrigerate for 1 hour. Meanwhile, preheat the oven to 350F or 180C
After the cookie dough is chilled, roll the cookie dough balls. Press it slightly to flatten it out. Stuff a chopped marshmallows in the center of the cookie. Stuff more chocolate chips around it. Pop it in the freezer for 20 more minutes and then bake for 10 minutes
After the cookies have been baked, allow them to stay in the same hot baking dish for 5 minutes on the counter, so that they harden a little. Drizzle with some chocolate syrup or melt some dark melting wafers in the oven and drizzle over your baked cookies. Allow the chocolate drizzle to harden for some time and then serve!
The cookie dough should be dry. Just add the mentioned amount of milk and do not freak out if it's too dry. The cookies will turn out just fine. (see the video for a visual)
You can store these cookies on the counter at room temperature for 3-4 days.
You can roll the cookie dough balls, flatten it out, stuff with the chocolate chips and Marshmallow, and freeze the cookies by wrapping them individually with aluminum foil and then store them in a freezer friendly bag. These will stay good for about 1 week.
Before baking, do not thaw. Just pop these cookies directly in the oven and bake for 3 extra minutes.