Preheat the oven to 350 degrees. Add parchment paper to a 13X9 inch baking pan. Leave a few inches of the paper over the edges to easily lift the bars out once they've cooled.

Whisk the baking powder, flour, and salt in a bowl.

Cream the butter, sugar, and brown sugar in a different bowl until smooth.

Mix in the eggs and vanilla.

Slowly add the flour mixture until combined.

Spread half of the cookie bar dough into the prepared pan.

Put the marshmallow creme in a microwave-safe bowl and heat for 20 seconds.

Spread the marshmallow creme evenly over the dough, and then sprinkle on the graham cracker crumbs.

Break the chocolate bars into pieces and lay them on top of the crumbs.

Sprinkle on the chocolate chips and then put any remaining dough on top. Press down to spread evenly.

Put the pan in the oven and bake for 25-30 minutes or until an inserted toothpick comes out clean.