Brötchen

I made my first batches of Brötchen ever and used King Arthur's European-style bread flour.  Altho I need much more practice forming the rolls, they were crispy and had a nice color on the outside.  However, the crumb was dense and chewy not like the soft and airy texture I remember.  I used the white flour Master Recipe from 'Artisan bread in five minutes a day' with one variation; adding 3 egg whites.  How can I get a softer and airier crumb?