2 cups all-purpose flour
2 cups graham cracker crumbs
1 teaspoon baking powder
1/4 teaspoon salt
16 tablespoons (2 sticks) butter, room temperature
1 1/2 cups packed light brown sugar
1 teaspoon vanilla
2 large eggs
2 cups marshmallow topping, Marshmallow Fluff or Creme (7 ounce container)
2 cups milk or semisweet chocolate chips
Preheat the oven to 350. Line a 9X13-inch pan with foil, leaving a 2-inch overhang on the 2 short sides. Grease the foil with cooking spray and set aside.
In a medium bowl, whisk together the flour, graham cracker crumbs, baking powder and salt.
In a large bowl, using an electric mixer on medium speed, beat the butter and sugar until light, about 2 minutes. Beat in the eggs and vanilla until well combined. Reduce the mixer speed to low and add the flour mixture, mixing just until combined.
Divide the dough in half. Press half into the bottom of the prepared pan until the dough is evenly flattened.
Dollop the marshmallow topping on top of the cookie base and gently spread into an even layer. Sprinkle the chocolate chips on top.
Scatter the remaining dough over the top in clumps. Don’t worry about completely covering the top.
Bake the bars until golden brown, about 30-32 minutes. Cool completely. Remove from the pan with the foil, cut into bars, and serve.