Heat oven to 350 degrees (325 for dark or non-stick pans). Place paper baking cups into each of 24 refular sized muffin cups/.
In large bowl, beat cake mix, water, vegetable oil, eggs and peanut butter on low speed for 30 seconds and then medium sped for 2 minutes, scraping bowl occasionally. Divide batter evenly among muffin cups (2/3 full).
Bake 20-25 minutes or until toothpick comes out clean. Remove from pan to cooling rack and cool completely (30 minutes).
In a medium bowl, stir together frosting and 1/4 cup peanut butter. Frost cupcakes with frosting mixture and sprinkle with peanuts. Press peanuts lightly into frosting.