For the cupcakes:

1. Preheat the oven to 350°F. Line a cupcake pan with cupcake liners.
2. In a large mixing bowl, combine the sugar, vegetable oil, eggs and vanilla extract. Beat on medium speed until the eggs and oil are well incorporated and the batter is lighter in color, about 2 minutes. Scrape down the bowl as needed. Next mix in the sour cream and beat until well combined.
3. In a separate bowl combine the remaining dry ingredients: flour, baking powder and salt. Add half the dry ingredients, and half of the milk and mix just until the flour starts to incorporate. Add the remaining ingredients and mix until well combined. Use a spatula to scrape down the sides of the bowl and stir the batter from the bottom to the top to ensure it’s well mixed.
4. Using a large cookie scoop, divide the batter evenly, filling each liner 2/3 full.
5. Bake at 350°F for 14-16 minutes. Test the cupcakes for doneness by inserting a toothpick into the center of the cupcake. If the toothpick comes out clean, the cupcakes are done. Cool Completely.

For the frosting:

1. Cut the butter into tablespoon-sized pieces. Using the paddle attachment, whip butter for 3-4 minutes, scraping down the bowl occasionally. Beat until the butter looks light in color. Next, beat the peanut butter until well mixed.
2. Slowly add the powdered sugar, 2 cups at a time, adding the heavy cream and vanilla intermittently, mixing on low speed until it’s incorporated into the butter. Then increase the speed to high and beat for 30-60 seconds. Repeat until all your powdered sugar has been added.
3. Lastly, add the marshmallow crème and beat until it’s well incorporated. 

To assemble:

1. Remove the centers using a cupcake corer. Save the tops of the cupcakes to the side.
2. Fill a large piping bag with marshmallow crème and use the piping bag to fill the centers of the cupcakes. Gently push the top of the cupcake back on top of the filling and frost. 
3. Add the frosting first, using a large piping bag fitted with a large open round piping tip to decorate, then roll in peanuts. Chop the peanuts into small pieces. Hold the cupcake in one hand and fill your other hand with peanuts. Gently press the peanuts into the sides of the frosting.