Preheat your oven to 350°F (175°C). Line a baking sheet with parchment paper.
In a large bowl, cream together the softened butter and granulated sugar until light and fluffy.
Mix in the vanilla extract, then gradually add the sifted all-purpose flour until a dough forms.
Roll out the dough on a floured surface and cut into circles using a round cookie cutter.
Place the cookie dough circles on the prepared baking sheet and bake for about 10-12 minutes or until they are light golden brown.
Let the cookies cool completely on a wire rack.
Once cooled, spread marshmallow fluff on the flat side of half of the cookies.
Top with another cookie, flat side down, to create a sandwich.
Dip each sandwich into the melted chocolate chips, coating completely.
Place on a wire rack until the chocolate is set.