Preheat oven to 350 degrees Fahrenheit. Line a 9×13-inch pan with parchment paper, leaving a 2-inch overhang on the sides.
Blend graham crackers into crumbs with a food processor or blender. Combine with flour, baking powder, and salt. Set aside.
Cream butter, brown sugar, and granulated sugar. Beat in eggs and vanilla.
Add the flour mixture and mix until combined.
Press two-thirds (just over half) of the dough into the prepared pan. Spread the marshmallow fluff on top and sprinkle with chocolate chips. Place the remaining dough over the top in clumps. Do not cover it all. Leave marshmallow and chocolate chips peeking through.
Bake at 350˚F for 30-35 minutes until a deep golden brown. Cool completely. Use parchment paper to lift out of pan, then cut into bars.