Pre heat oven to 375 F. Use a paper towel to wipe non-stick spray or a tiny bit of vegetable oil into each cup of a mini muffin tin. If using paper liners, place directly into pan with no oil.
In a medium mixing bowl – sift together or whisk the dry ingredients. In a second mixing bowl combine the oil, vanilla, milk, pumpkin, and orange zest. Add the dry ingredients to the wet ⅓ at a time. Mix until batter is a uniform color and texture.
In a small bowl – whisk the egg whites until very frothy. Fold egg whites into batter, gently stirring until completely incorporated.
Spoon just under a tablespoon of batter into each muffin cup, filling each a hair under ¾ full.
Bake muffins in preheated oven for about 12 minutes. Finished muffins will be springy to the touch.