In a large bowl of a stand mixer, whisk together 1 & 1/2 cups of the flour and the yeast; set aside briefly. Meanwhile, in a medium saucepan, heat and stir the milk, mashed potatoes, 1/3 cup butter, sugar, and salt until warmed and butter is just barely melted, about 120 degrees F. Pour the melted butter mixture into the bowl with the flour and add in the eggs.

Beat with the dough hook attachment on low speed for 30 seconds, scraping the sides of the bowl as necessary. Once combined, beat on high speed for 3 minutes, stopping the mixer to add in as much of the remaining flour as you can, saving some for kneading. NOTE: to avoid tough cinnamon rolls, use the flour conservatively, starting with the smaller amount and slowly adding where needed.

Turn the dough onto a lightly floured work surface and knead in the remaining flour until dough is soft and elastic, about 3-5 minutes of kneading time. Shape the dough into a ball and place in a lightly greased bowl, turning once to grease the whole surface of dough. Cover and let rise in a warm place until double in size, roughly 45-60 minutes.

Punch the dough down and turn the dough onto a lightly floured work surface. Cover the dough and let rest for 10 minutes. Meanwhile, lightly grease a 13x9" rectangular baking pan with cooking spray. In a small bowl, stir together the brown sugar and cinnamon for the filling.

Roll out the dough into a large rectangle, about 18x12". Spread the softened butter over the surface of the dough and sprinkle liberally with the brown sugar & cinnamon mixture. Starting from the long side of the dough, begin tightly rolling the dough into a roll. Pinch seams closed. Cut dough spiral into 12 equal pieces using either a sharp serrated knife or dental floss. Place the cut rolls into the prepared pan. Cover with another clean kitchen towel and let rise in a warm place until doubled (about 30 minutes).

Preheat your oven to 350 degrees F. Bake for 20-25 minutes or until golden brown and they appear done in the center. Let set for 10 minutes before topping with the icing.

For the icing: In a small saucepan, melt the butter over medium heat. Once butter has melted, pay close attention as the mixture is prone to burning quickly. Watch the butter bubble, foam and fizz, stirring and swirling the pan often, until browned bits appear on the bottom of the pan. Remove from heat when the butter is amber in color and nutty in fragrance. Pour the browned butter into a medium bowl with the remaining icing ingredients and whisk to combine. Spread on top of still-warm rolls.