You will also need a rotary-style cheese grater and a wire mesh cooling rack. Read the directions before starting so you're comfortable with the steps.
Separate the Nutter Butter cookies and scrape away the peanut filling -- use a knife or spatula. Save the filling for another use or use it in place of some of the peanut butter in the peanut butter "fudge." You could leave the cookies whole, but you'd have very thick slippers.
Grate 4 ounces of the candy melts using a rotary-style cheese grater. Place shavings in a bowl.
Make the peanut butter "fudge." Combing the peanut butter, butter, cream, and salt in a microwave-proof bowl. Microwave for 30 seconds, then stir. If butter is not completely melted, microwave 20 more seconds. Stir. Next add powdered sugar 1/3 cup at a time, stirring after each addition. Kneading with your hands if necessary. Stop when you have a nice, pliable consistency. You don't want the fudge to be too dry. A little less than 1 cup of powdered sugar worked for me. If it's too dry, add a tiny bit of cream and stir/knead.
Using a mini ice cream scoop or teaspoon, divide the peanut butter fudge into 30 balls (about 2 teaspoons each). Place the ball on the end of a cookie. Form the ball into the front part of the slipper, pinching/sealing the front edges to the cookie. Use the end of a wooden spoon (or your finger) to hollow out an indentation where a foot would slide into the slipper.
Lay a large piece of parchment paper on the counter top. Place a wire mesh cooling rack over the paper.
Melt the remaining 16 ounces of candy coating in the microwave (or double boiler) per the directions on the package.
Dip each slipper into the candy coating, making sure all the crevasses are coated, especially the inside of the slipper. Shake off excess and place on wire mesh rack. Repeat with remaining slippers. For the next step, the candy coating should not completely set, but it should not be too hot or it will melt the shavings.
Using a spoon sprinkle the shavings over the slippers. You may need to pick up each slipper to sprinkle shavings over the sides. If you run out of shavings, use the shavings that fall below the wire mesh cooling rack.
Freeze the slippers for 5 minutes to set, then bring to room temperature and serve.