Place your sweet potato chunks in a pan and cover them with cold water. Boil for about 20 minutes or until fork tender. Drain and return sweet potato chunks to a bowl or your pan. Mash until smooth and set aside.
In the bowl of an electric mixer, combine yeast, warm water, olive oil, and 1 tablespoon honey. If you pour your olive oil into your tablespoon measure first, and swirl it around, the honey will come out easier after it's been measured.
Give this all a quick stir and allow it to sit for 15 minutes to get foamy.
To your foamy yeast mixture, add your mashed sweet potatoes, remaining tablespoon of honey, buttermilk, melted butter, and salt. With your mixer on low, combine all of these ingredients.
With your mixer still running, start adding in the flour a half cup at a time and mix until combined.
Once all your flour is incorporated, turn off your mixer and switch out your paddle attachment for your dough hook. Use that to knead your dough for two to three minutes. It will still be quite sticky, but that's okay.
Transfer your dough to a lightly greased bowl. Cover it with plastic wrap or a clean tea towel and set it aside in a warm place for two hours to rise.
Turn your dough out onto a lightly floured surface and knead it until smooth. Roll it out into a fat log and cut off approximately two ounce pieces, rolling them into a ball. Place your rolls into a greased 9x13 baking pan.
Allow your dough to rise in a warm place for another 30-45 minutes.
Preheat your oven to 375F (190 C).
Use a pastry brush to brush the top of each roll with your beaten egg.
Bake for 20-25 minutes or until lightly golden on top. Serve warm or store in an airtight container and reheat before serving.