Preheat oven to 350°F. Line a 13x9-inch baking pan with foil, leaving a 2-inch overhang on the 2 short sides. Grease and set aside.
In a medium bowl, combine flour, graham cracker crumbs, baking powder and salt. In a large bowl, beat butter and sugar until light and fluffy. Beat in eggs and vanilla until well combined.
Change mixer speed to low and add flour mixture, mixing until combined. Divide dough in half. Press half into the bottom of the prepared pan until dough is evenly flattened.
Dollop the marshmallow topping over top of the dough and spread into an even layer. Sprinkle chocolate chips on top
Sprinkle the remaining dough over top in clumps not worrying about completely covering the top. The marshmallow and chocolate chips should peek through.
Bake 30-32 minutes or until golden brown. Cool completely.
Remove bars from pan using the foil to lift out. Cut into bars to serve.