Preheat the oven to 350°F (175°C)., Line two baking sheets with parchment paper., In a large mixing bowl, whisk together the all-purpose flour, baking powder, and salt., In another bowl, cream together the softened butter, granulated sugar, and brown sugar until light and fluffy., Beat in the eggs one at a time and add the vanilla extract, mixing until combined., Add the Nutella and mix until fully incorporated., Gradually fold the dry flour mixture into the wet ingredients until just combined., Gently fold in the mini marshmallows until evenly distributed., Scoop the dough onto the prepared baking sheets, leaving about 2 inches of space between each cookie., Bake for 10-12 minutes, or until the edges are golden brown and the centers look just set., Let the cookies cool on the baking sheets for about 5 minutes before transferring them to a cooling rack.