Peel and cube potato, boil until tender (15-20 minutes), drain and reserve 1/2 cup potato water.
Mash potato and let cool to warm. You need 1/2 cup mashed potato.
In stand mixer bowl, combine warm milk, yeast, and honey. Let sit 5 minutes until foamy.
Add potato water, mashed potato, oil, salt, and 1 cup flour. Mix together.
Add remaining flour 1/2 cup at a time until dough forms a ball and pulls from bowl sides.
Knead in mixer 5-8 minutes until smooth and slightly tacky.
Form dough into ball, place in greased bowl, cover with plastic wrap.
Let rise until doubled, about 1.5-2 hours.
Deflate dough and flatten into 8x10 inch rectangle. Roll into log, pinch seam, tuck ends under.
Place in greased 9x5 inch bread pan, cover, and let rise until doubled, 30-45 minutes.
Preheat oven to 350F.
Bake 40-45 minutes until golden brown and sounds hollow when tapped.
Cool in pan 5-10 minutes, then turn out onto cooling rack.
Let cool completely before slicing.