In a small bowl, mix 1 cup bran with the boiling water, stir, and let it sit for 5 minutes.
In a separate bowl, cream butter and brown sugar together until smooth.
Measure and combine the flour, baking soda, and salt in another bowl with a whisk. In a 1-cup glass measuring cup, combine the cold water and chia seeds to make an egg substitute. Whisk and let sit 2 minutes.
Combine the moist bran with the egg substitute, remaining 2 cups of bran, buttermilk, creamed mixture, and the flour mixture. Mix thoroughly with a spoon until everything is completely mixed in. If you want to save the batter for later use, now would be the time to put the batter in an air-tight container and refrigerate for 2-4 weeks.
Preheat oven to 400° F. Scoop batter into prepared muffin cups and bake for 15 minutes or until a toothpick inserted into the center comes out clean.
Notes
If you can't find organic buttermilk, try letting a mixture of 1 cup organic milk with 1 tablespoon vinegar for 5 minutes.