1. Heat oven to 350Â°F (325Â°F for dark or nonstick pans). Place paper baking cup in each of 24 regular-size muffin cups.
2. In large bowl, beat cake mix, water, oil, eggs and 3/4 cup peanut butter with electric mixer on low speed 30 seconds. Beat on medium speed 2 minutes, scraping bowl occasionally. Divide batter evenly among muffin cups (about 2/3 full).
3. Bake 20 to 25 minutes or until toothpick inserted in center comes out clean. Remove from pan to cooling rack. Cool completely, about 30 minutes.
4. In medium bowl, stir together frosting and 1/4 cup peanut butter. Frost cupcakes with frosting mixture. Sprinkle with peanuts; press lightly into frosting.