I have been making this for years and have just had success with it from the above book.
My tweaks & hints are as under.
I used plain white flour, eggs at room temperature and added some cream of tartar to help increase volume.
Beat the egg whites with the addition of 1/2 tspn cream of tartar on speed 3/temp 37o/4 mins, MC out.
Use reverse when adding the almonds and flour.
Baked the loaf in an 11 x 21cm loaf tin for 30 minutes.
Cut the slices 2mm thick - you need a very good bread knife for this.
Leave on the tray to cool then store in an airtight container and only take out what you need, don't leave the container lid off for too long or they will soften, especially in high humidity areas.
Makes heaps and they are a great addition to Christmas goodie baskets. I buy small plastic containers for this purpose as they will not stay crisp just wrapped in cellophane. For Christmas you can use pistachios instead of almonds and add some glace cherries for a Christmassy feel.