Preheat your oven to 375°F (190°C).

Combine whole wheat flour, bran flakes, baking powder, cinnamon, and brown sugar in a large bowl.

Whisk together the egg, milk, and melted butter in another bowl until smooth.

Pour the wet ingredients into the dry mixture and gently stir until just combined.

Spoon the batter into greased muffin tins, filling each about two-thirds full.

Bake for 18-20 minutes or until a toothpick inserted into the center comes out clean.