Applesauce makes these muffins extra-tender. Fresh diced apple adds a refreshing pop of flavor.
Preheat oven to 350 degrees. Line a standard 12-cup muffin tin with baking cups, or lightly brush with butter. In a medium bowl, whisk together flour, wheat bran, millet, baking soda, and salt. In another bowl, whisk together butter, brown sugar, egg, and applesauce. Stir wet ingredients into dry until just combined. Fold in apple.
Divide batter evenly among muffin cups. Bake until golden and tops spring back when lightly touched, about 24 minutes. Let cool 5 minutes in tin, then transfer to a wire rack and let cool completely.