Preheat oven to 350°F. Line a 9x13 casserole dish with parchment paper.
In a large mixing bowl, cream together sugar and butter. Add eggs and vanilla
extract and beat on high speed for 2 minutes.
Mix together flour, salt, and baking soda and add to the butter mixture. Beat just
until combined.
Press sugar cookie dough evenly across the bottom of prepared 9x13 baking dish. Bake at 350° for 15 minutes.
In a medium mixing bowl, beat together cream cheese, peanut butter, powdered sugar, vanilla extract, and sour cream until thoroughly combined.
Pour 2 cups of heavy whipping cream into a chilled mixing bowl. Beat on medium high speed (either with a standing mixer whisk attachment or with a handheld mixer) until stiff peaks form.
Use a spatula to gently fold the whipped cream into the peanut butter cream cheese mixture.
Spread the peanut butter cheesecake filling evenly over the cooled sugar cookie crust.
Place dish in the refrigerator for at least 4 hours or in the freezer for at least 2 hours to set.
Warm peanut butter for topping the fluffernutter bars in the microwave until runny.
Drizzle peanut butter and marshmallow cream over the top of the chilled bars
Load peanut butter and marshmallow cream into Ziploc bags and snip off the corner for easy drizzling.
Sprinkle with peanut butter and/or butterscotch chips.
Cut into bars and serve.