These are prize-winning blue ribbon cinnamon rolls that have won multiple years in a row at the Iowa State Fair. The contestant won so many times that she now has shared the recipe with her fans! Thanks Sarah! I love that they make 2 pans, since you go through the work you get lot's of reward!
Combine butter, salt, sugar, hot water, hot potato water, and hot mashed potatoes into a bowl and stir until the butter melts.
In a separate bowl, combine the yeast with the warm water and allow time to activate. Add yeast mixture to the potato water mixture and stir. Stir in beaten eggs. Next, add flour to the water mixture, one cup at a time, stirring after each cup, until a soft dough forms.
Turn out onto a floured surface and start kneading until smooth, about seven minutes. Place dough into a greased bowl, turning o grease all sides. Cover, and let rise until double, about 1 hour.
Roll dough into a long rectangle and spread softened butter over top. Combine cinnamon and sugar and sprinkle over top of dough. Roll up jelly-roll style, long way, and cut into 24 equal pieces. Place rolls into two 9x13 pans. Cover and let rise until double, about 30 minutes. Bake in a 350-degree oven until golden brown, about 25-30 minutes.
Let rolls cool for about 10 minutes. Combine frosting ingredients and spread over rolls.