Preheat oven to 350°F. Line a large baking sheet with parchment paper.

Mix together Dark Chocolate Chunk Cookie Mix with butter, egg and water and until well combined. Fold in dark chocolate chips and walnuts.

Place the dough in the freezer for 10 minutes to firm up the dough.

Meanwhile, chop or cut (with scissors) the marshmallows into fours. You can also choose to use mini marshmallows to avoid this step.

Once dough has been chilled, scoop about 2 ½ tablespoons of dough, and roll into balls using your hands. This will make about 12 large dough balls. If dough is sticking to your hand, place in the fridge or freezer for a few more minutes.

Once rolled, 6 on the baking sheet, leaving a couple of inches in between each to allow them to spread out while baking. Garnish with a few chocolate chips and walnuts to make it extra delicious and pretty.

Bake for 8 minutes, then pull out of the oven. Top with 3-4 marshmallow pieces, cut side down, and place back in the oven for another 1-2 minutes, or until marshmallows are gooey and the cookies appear to be mostly cooked through. Cookies will continue to cook slightly once taken out of the oven while they are cooling on the baking sheet.

Let sit on the baking sheet for 10 minutes before transferring to a cooling rack. These will fall apart if moved too soon.