Heat butter and milk over low heat until butter melts and the mixture is warm. Remove from heat and cool about 10 minutes.
Add the two packages of yeast to the milk. Stir it and then let it sit for 5-10 minutes.
In the mean time, combined mashed sweet potato and eggs with an electric mixture.
In another bowl, whisk together white sugar, flour, cinnamon, nutmeg, and cardamom.
Add the flour mixture to the sweet potato mixture, about 1/2 cup at a time, mixing in between each addition. Make sure the dough is slightly sticky to the touch and doesn't get overly dry.
Slowly pour the yeast mixture into the flour and mix in - do not overmix!
Using a dough hook, knead the dough for about five minutes. Alternatively, you can use hand kneading. I just think a dough hook is easier!
Place in a greased bowl, cover, and let rise for about an hour.
After an hour, punch the dough down and roll into a large rectangle, about 1/2 of an inch thick. Make sure the surface you roll it on is well-floured so it doesn't stick.
Using softened butter, spread butter liberally on the dough.
Mix together the pecans, brown sugar, and cinnamon, and spread evenly on top of butter/dough.
Roll up, and cut into slices. Place on a greased pan.
Bake at 350 degrees for about 20-25 minutes.
Remove from oven. While cooling, prepare the glaze.
Combine sugar and water in a pot and heat until boiling. Stir until sugar dissolve.s.
Whisk in marshmallow cream and butter until everything is combined. Let it lightly boil for a minute or two, whisking the entire time.
Remove from heat and let cool for 30 seconds to a minute.
Drizzle on top of warm rolls.