Activate the yeast: In a bowl, combine warm milk (about 110°F/45°C) and sugar. Sprinkle yeast on top and let it sit for 5-10 minutes until frothy.

Mix wet ingredients: In a large mixing bowl, combine the yeast mixture, softened butter, eggs, salt, and mashed sweet potato. Stir well.

Add flour: Gradually add the flour, about 1 cup at a time, stirring until a soft dough forms. You might not need all the flour.

Knead the dough: Turn the dough onto a floured surface and knead for 5-7 minutes, until smooth and elastic.

First rise: Place the dough in a lightly greased bowl, cover it with a damp towel, and let it rise in a warm place for about 1 to 1.5 hours, or until doubled in size.

Prepare the filling: In a medium bowl, mix the mashed sweet potato, brown sugar, cinnamon, vanilla, nutmeg, ginger (if using), and a pinch of salt until smooth and well combined.

Roll the dough: Once the dough has risen, roll it out on a floured surface into a large rectangle (about 16x12 inches).

Spread butter: Spread softened butter evenly over the dough.

Sprinkle the filling: Evenly spread the sweet potato filling over the buttered dough.

Roll and cut: Roll up the dough tightly, starting from the longer side. Cut into 12-15 rolls.

Second rise: Place the rolls in a greased baking dish, cover, and let them rise for another 30-45 minutes, or until puffy.

Preheat the oven: Preheat the oven to 350°F (175°C).

Bake: Bake the rolls for 25-30 minutes, or until golden brown on top. Let them cool slightly before icing.

Make the icing: Beat together softened butter, cream cheese, powdered sugar, vanilla, salt, and cinnamon (if using) until smooth and creamy.

Ice the rolls: Spread the cream cheese icing over the warm rolls.