Preheat oven to temperature as directed on box mix. Prepare the cupcake batter as directed on the box mix. Spoon batter into cupcake liners but only filling 1/3 full (use about half the batter, save half for the top). Drop a peanut butter Oreo into each cupcake. Fill each cupcake another 1/3 full or until the rest of the batter is used.
Add the salt and heavy cream, mix until smooth. Increase speed to high for 2-4 minutes until it becomes fluffy and the color gets lighter. If not thick enough, add more powdered sugar. Stiff peaks should form.
Frost as desired and top with a 1/4 piece of a peanut butter Oreo cookie...if there are any left...
Store in refrigerator.
If serving the following day, I would hold off on adding the Oreo topper until just before serving otherwise they will get soggy.
This makes A LOT of frosting. If you're not planning to use a lot and not pipe the frosting to get some height, you could almost cut the frosting recipe in half.