1. Preheat oven: Preheat your oven to 350°F (175°C). Line a muffin tin with cupcake liners.
2. Combine ingredients: In a large bowl, combine the cake mix, peanut butter, milk, and eggs. Beat until smooth.
3. Fill muffin tins: Fill each cupcake liner about 2/3 full with batter. Sprinkle with chopped peanuts, if desired.
4. Bake: Bake for 18-20 minutes, or until a toothpick inserted into the center comes out clean.
5. Cool: Let the cupcakes cool in the muffin tin for a few minutes before transferring to a wire rack to cool completely.
6. Frost and enjoy: Frost the cupcakes with your favorite frosting and enjoy the perfect balance of chocolate and peanut butter bliss!
