nachas, I never tried substituing this recipe with whole wheat flour. I have a different whole wheat recipe – which is drier than my regular challah recipe.
2 1/4 Cups lukewarm water
7 1/2 teaspoons yeast
12 Tablespoons olive oil (alternate with honey)
9 heaping Tablespoons honey (if you alternate with olive oil the honey will slide off the spoon)
3 eggs
9 Cups whole wheat flour
3 3/4 teaspoons salt
Same instructions as any challah recipe. My tricks are the same: beat all ingredients with half the flour and salt with a regular cake beater then switch to the dough hook when you add the remaining flour. When you punch it down after 1 hour, put it back on the mixer with the dough hook.
Personally, I don’t do an egg wash on whole wheat challah, I find that it gets a little sticky.