Preheat the oven to 350°F, and lightly coat 12 muffin cups with nonstick spray.
In a medium bowl, stir together the oat bran, Greek yogurt, ½ cup of milk, and vanilla extract. Let the mixture rest for at least 10 minutes while preparing the remaining ingredients.
In a separate bowl, whisk together the flour, baking powder, baking soda, cinnamon, nutmeg, and salt. In a third bowl, whisk together the coconut oil and egg whites. Stir in the molasses and maple syrup. Add the oat bran mixture, stirring until fully incorporated. Alternate between adding the flour mixture and remaining ¼ cup of milk, beginning and ending with the flour mixture, and stirring just until incorporated. (For best results, add the flour mixture in 3 equal parts.) Fold in the carrots and raisins.
Evenly divide the batter between the prepared muffin cups. Bake at 350°F for 18-20 minutes or until the tops feel firm to the touch. Cool in the muffin cups for 5 minutes before carefully transferring to a wire rack.
