In a large measuring cup, mix together the milk and honey. Mix in the yeast and set aside for five minutes.
In the bowl of a stand mixer, whisk together the mashed potatoes, egg and butter. Whisk in the milk, honey and yeast mixture.
Add in the flour and salt and knead on medium speed for 8-10 minutes using the dough hook, or until mixture is smooth and slightly sticky. Remove dough and coat the inside of the bowl with oil. Place dough ball back into the bowl, cover with plastic wrap and set aside to rise for an hour and a half to two hours or until double in size. (I like to turn my oven on, let it preheat for one minute, turn it off and set the dough in the oven for a quicker rise. I find this usually gets the job done in an hour.)
After the dough has risen, butter the bottom and sides of an 8 x 8 pan. Portion dough into nine equal portions (use a kitchen scale or eyeball it), rolling each piece into a smooth ball. Place into buttered pan and cover lightly with plastic wrap. Set aside to rise for an additional hour.
While rolls are rising, preheat oven to 350 degrees.
If desired, brush rolls with an egg wash (one egg mixed with one tablespoon of water). This isn't necessary, but it will
Bake in preheated oven for 25-30 minutes or until golden brown.
Turn rolls out onto cooling rack immediately. Allow to cool for five minutes before serving.
