Preheat oven to 350F
Grease 3 9" round cake pans with butter and flour.
In a large bowl, cream butter and shortening.
Add coconut extract and mix through.
Gradually add the sugar as you are still beating. Set your bowl aside.
In a separate bowl sift together the flour, baking powder, and salt.
Gradually add the dry ingredients to the creamed sugar bowl alternating with the milk (1/4 cup at a time). Beat thoroughly between each ingredient.
In a third bowl beat the egg whites until they form stiff peaks. Gently fold them into your cake batter.
Pour the cake mixture evenly between the pans and bake for approximately 25 minutes.
Sift the confectioners sugar into a bowl. Add the softened butter and coconut extract and mix. Add 1 tablespoon of milk at a time until your icing is thick but spreadable.