Preheat your oven to 350°F (175°C).

In a large mixing bowl, cream together the softened unsalted butter, granulated sugar, and brown sugar until light and fluffy.

Beat in the eggs one at a time followed by the vanilla extract.

In another bowl, whisk together the all-purpose flour, cocoa powder, baking soda, and salt. Gradually add this mixture to your wet ingredients while stirring continuously until combined.

Gently fold in the semi-sweet chocolate chips using a spatula.

Scoop out about two tablespoons of dough and flatten it slightly in your palm. Place approximately one teaspoon of Nutella and one teaspoon of vegan marshmallow fluff in the center before sealing it with more dough.

Place your stuffed cookies on parchment-lined baking sheets about two inches apart. Bake for about 12 minutes or until the edges are set but the centers remain soft.

Let your cookies cool on the baking sheet for a few minutes before transferring them to wire racks to cool completely.