In a small bowl, combine the warm milk or water with the yeast and sugar. Stir to combine and then let it sit for about 10 minutes to activate the yeast.
Measure out the cassava flour, arrowroot starch, and salt into the bowl of a mixer. Mix it on low to add extra air to the flour.
Add the eggs to the yeast mixture and whisk slightly, then add the mixture to the dry ingredients.
Cut the butter into the dough until a soft, but pliable dough has been formed.
Shape the dough into the shape you want. (see notes above on shaping). Using a sharp knife cut some slits on the top of the dough.
Cover the dough with a kitchen towel and place it in a warm spot for an hour to let it rise.
Once the dough has risen (it will look puffy), preheat the oven to 400 degrees. Brush the top of the dough lightly with melted butter or olive oil if desired.
Bake the bread in the oven for about 25 minutes or until the internal temperature reaches 205 degrees.
Let cool about 5 minutes, slice and enjoy it warm!