Preheat the oven to 350 degrees F. Prep a standard muffin tin with paper liners or mist with oil spray. Set aside.
Puree the beans and 1 cup water in a high-powdered blender. Add the cake mix and dates to blender and combine until smooth, 1 minute.
Stir in the nuts by hand, if using. Pour the batter into the prepared muffin tins about three quarters of the way high and bake for about 18 to 24 minutes or until an inserted toothpick comes out clean. (See Cook's Note.) Let cool completely.
To finish: Top each cupcake with 1 to 2 tablespoons frosting.
Cook cupcake batter immediately or the angel food cake will deflate, and you'll wind up with flattened (albeit delicious!) cupcakes.