• Preheat oven to 350°F.
• Line an 8x11 inch baking pan with parchment paper, allowing the parchment paper hang over all the edges of pan, so that you can use it to pull the bars out of the pan later.

To make the cookie dough:

• Combine the butter and sugar in a large bowl and beat until light in color and fluffy consistency (about 3 minutes).
• Add the egg, peanut butter and vanilla, continuing to mix.
• Add the flour and mix until well combined.
• Fold in chocolate chips.

To make the fluffernutter bars:

• Press about 2/3 of the dough into the bottom of the baking dish.
• Spread the entire container of marshmallow creme over the layer of Reese's cups.
• Place the peanut butter cups on top of the cookie dough, in an even layer, not overlapping.
• Spread the marshmallow fluff on top of the peanut butter cups, spreading evenly.
• Cover with the remaining dough and gently press into an even layer.
• Bake for 25 minutes at 350°F until the crust starts to turn golden brown. 
• Remove from oven, keeping bars in the pan for an hour. This allows them to slowly cook a little more until they cool to room temperature.
• Remove the fluffernutter bars from the pan by pulling on the parchment paper and place on a wire cooling rack. Allow to cool fully, until set, before slicing.