Preheat oven to 350 degrees and spray a mini muffin tin or standard loaf pan with nonstick spray.
Place the dates and water in a small saucepan, uncovered, over high heat. As soon as the mixture comes to a boil, add the baking soda. Mixture will foam up; reduce the heat to medium or medium high if mixture starts to foam over. After a minute or two, the dates should begin to break down. Use a wooden spoon to stir/mash up the dates a little. Let simmer for another five minutes or so until the dates break down into a paste-like mixture. Add an additional splash of water if the mixture starts to look dry before the dates have completely broken down. Once dates are a stir-able mass, set aside to cool.
In a large bowl, combine the flours, cocoa, baking soda, baking powder and salt. Add the date paste, vanilla, milk, bananas, oil and peanut butter and stir until well combined. Do not overmix. Fold in chocolate chips.
Place about a heaping tablespoon of batter into each mini muffin well or pour batter in prepared loaf pan. Bake for 12-13 minutes for mini muffins or about 40-45 minutes for a loaf. Muffins are done when the tops feel firm to the touch.