Mix flours and cocoa powder in a large bowl and set aside. Sprinkle the yeast over the lukewarm coffee and let sit for about 5 minutes.
Add the flour mixture to the yeast mixture and mix until combined. Add more spelt flour as needed to make a slightly sticky, but firm dough.
Turn dough out onto a floured table and knead until elastic (8-10 minutes). Place dough into a large oiled bowl, turn to coat and cover. Let rise until doubled in size, about 1 hour.
Turn dough out onto a lightly floured surface. Cut dough in equal halves and form into two round balls. Place onto a parchment lined baking sheet. Cover and let rise 45 minutes to 1 hour or until doubled in size.
Preheat oven to 375°F.
Brush dough balls with egg wash (1 egg beaten with 2 tablespoons cold water). Sprinkle with sesame seeds.
Bake for 30 minutes or until loaf sounds hollow when tapped on bottom and the internal temperture is about 205°F. Remove to a rack to cool.
