S'mores Bars

1. Prep the Pan: Preheat oven to 350°F (177°C) and line an 8- or 9-inch square pan with parchment paper.
2. Make the Dough: Cream butter and brown sugar until light and fluffy. Add the large egg and vanilla extract, mixing until just combined. In a separate bowl, whisk together the all-purpose flour, graham cracker crumbs, baking powder, and salt. Gradually add the dry ingredients to the wet ingredients, mixing until just combined.
3. Build the Base: Press about two-thirds of the dough evenly into the bottom of the prepared pan. The dough will be sticky, so it's best to use your hands.
4. Add the Fillings: Carefully spread the marshmallow fluff over the dough base. Sprinkle the semi-sweet chocolate chips evenly over the marshmallow layer. Crumble and patch the remaining one-third of the dough on top of the chocolate chips, allowing some of the gooey marshmallow and chocolate to peek through.
5. Bake & Cool: Bake for 25–30 minutes, or until the top is golden brown and the edges are set. Allow the bars to cool completely in the pan on a wire rack before lifting them out and slicing. Cooling completely is crucial for clean slices.