To heat treat the flour, spread it out on a baking sheet and bake for 5 minutes at 350°F.
In the bowl of a stand mixer or a large mixing bowl, combine the butter, cream cheese, and brown sugar. Mix with an electric mixer on medium-high speed until smooth, light, and fluffy.
Add the peanut butter, heat-treated flour, and vanilla extract to the butter mixture. Mix on medium-high speed until fully incorporated.
Mix in the powdered sugar and demerara sugar.
Gently fold in the chocolate chips, Reese’s Pieces, and mini Reese’s cups.
Transfer the dip to a serving dish and top with additional chocolate chips and peanut butter cups.
Serve immediately with your favorite dippers, such as pretzels, graham crackers, or fruit.