Preheat oven to 350°. Line 24 muffin cups with paper liners.
Beat first 5 ingredients until well blended. In another bowl, whisk together flour, baking soda, baking powder and salt; gradually beat into banana mixture. Fold in chocolate chunks.
Fill prepared cups three-fourths full. Bake until a toothpick inserted in center comes out clean, 20-25 minutes. Cool in pans 10 minutes before removing to wire racks to cool completely.
For frosting, beat cream cheese, peanut butter and butter until smooth. Gradually beat in enough confectioners' sugar to reach desired consistency. Spread over cupcakes. If desired, sprinkle with peanuts. Refrigerate leftovers.