Preheat oven to 425°F (220°C).

In a large bowl, combine oat bran, brown sugar, all-purpose flour, baking powder, pumpkin pie spice, and salt.

Stir the dry ingredients well.

Create a well in the center of the dry ingredient mixture.

In a separate bowl, combine mashed pumpkin, skim milk, beaten egg whites, and vegetable oil.

Pour the wet ingredients into the well of the dry ingredients.

Stir until just enough to moisten the dry ingredients. Do not overmix.

Spray a 12-cup muffin tin with vegetable cooking spray.

Fill each muffin cup about 2/3 full with the batter.

Bake in the preheated oven for 20 minutes, or until a wooden skewer inserted into the center comes out clean.