Sift the flour, baking powder, baking soda, spices and salt into a large mixing bowl. In another bowl mix the egg whites, pumpkin, oil, brown sugar, milk, yogurt, vanilla, apricots, and optional nuts. Add the wet ingredients to the dry ingredients, stirring as little as possible to incorporate. Divide the mixture among twelve muffins cups that have been greased or sprayed with a cooking spray. Bake in the middle of a preheated 400F (200C) oven for 20 to 25 minutes, or until the top of the muffins spring back when pressed.