Preheat the oven to 375 degrees. Line a rimmed baking sheet with parchment paper.
Melt butter in a small, shallow dish. In another shallow dish, stir together sugar and cinnamon.
Roll out crescents and divide along perforations. Place on the parchment paper.
Dip a marshmallow in the butter, then into the cinnamon sugar mixture, then place it in the center of the crescent. Repeat with remaining marshmallows.
Fold in the corners on the wide side of the triangle, then roll the crescent over the marshmallow towards the skinny end. Seal up all the edges super tight, making sure there are no holes.
Mix together any remaining butter and cinnamon sugar and brush it on the top of the crescents. Place in the oven and bake for 11-13 minutes or until crescents are light golden brown and puffy. Allow to cool slightly before serving.