Line 12 muffin tins with parchment cupcake liners. Set aside

In a microwave safe bowl, place 1 cup of your chocolate chips in the bowl. Melt the chocolate chips by heating them in 30 second intervals stirring in between until the chocolate is smooth.

Scoop out ½ tablespoon of melted chocolate and place it into the cupcake liner. I found it easiest to use two small spoons, one to scoop and one to scrape the chocolate off the other spoon. Spread your chocolate evenly over the bottom.

Freeze for 10 minutes.

While your chocolate is freezing, prepare the peanut butter filling. Place the peanut butter, powdered sugar, and unsalted butter into a mixing bowl. Using a handheld mixer, beat the mixture on medium speed until smooth.

Scoop 1-2 teaspoons of the peanut butter filling into the center of the chocolate layer. Gently flatten using a spoon and spread the filling evenly. Make sure to not get the filling onto the sides of the cupcake liner. Freeze for 10 minutes.

Remove from the freezer and top the peanut butter with 1 teaspoon of marshmallow fluff. Make sure to keep the fluff in the center of the peanut butter cup. Dip your finger into some water and gently smooth down the marshmallow fluff. Freeze for another 10 minutes.

While the marshmallow fluff is freezing, melt your remaining 1 cup of chocolate chips the same way you did in step 2. Once melted, top each cup with ½ tablespoon of chocolate, making sure you go all the way to the edge of the cupcake liners.

Freeze for a final 10 minutes to set.