Pre-heat oven to 190 C. + One x 2lb(900g) loaf tin, lined with a parchment loaf tin liner.
Sieve all dry ingredients together into a bowl. Add any extra millet flakes, husks or seeds left in sieve to flours. Add chopped thyme, roasted red pepper and spinach – gently mix.
Whisk whole egg, buttermilk, honey and oil together in a jug. Make a well in the flours - add almost all of the liquid. Stir dough with your hand in a circular movement; bring the excess flour from the outside of the bowl to the centre until all the flour is incorporated. Add whisked egg white and gently mix in to dough. Add more milk if necessary. (This mixture is quite wet).
Transfer the dough mixture into loaf tin. Place in oven for 15 minutes at 190c and then turn down heat to 150c for 30-40 minutes or until bread is cooked.
Allow to cool on a wire rack.