Preheat your oven to 175°C (350°F) and line a 23x33 cm (9x13 inch) baking pan with parchment paper, leaving some overhang for easy removal.
In a large bowl, cream together the softened butter, brown sugar, and granulated sugar until smooth and fluffy.
Add the eggs one at a time, mixing well after each addition, then stir in the vanilla extract.
In a separate bowl, mix together the flour, baking powder, and salt. Gradually add the dry ingredients to the wet mixture, stirring until just combined.
Fold in the chocolate chips and crushed graham crackers until evenly distributed.
Press half of the cookie dough into the prepared baking pan evenly.
Spread the mini marshmallows evenly over the dough layer, then top with the remaining cookie dough, spreading it gently to cover the marshmallows.
Bake in the preheated oven for 20-25 minutes, until the edges are golden brown and a toothpick inserted in the center comes out mostly clean.
Allow the cookie bars to cool completely in the pan. Once cooled, lift them out using the parchment overhang and cut into squares.
Notizen
Serve warm with a scoop of vanilla ice cream and garnish with extra graham cracker crumbs and chocolate syrup.