Activate the yeast: In a large bowl, combine warm milk, yeast, and 1 tablespoon of the sugar. Let sit for 5–10 minutes, until foamy.
Add the remaining sugar, mashed banana, egg, melted butter, and vanilla. Mix well.
Gradually add the flour and salt, stirring until a soft dough forms.
Knead the dough on a lightly floured surface for 6–8 minutes, until smooth and elastic.
Place the dough in a lightly greased bowl, cover, and let rise in a warm place for 1–1½ hours, or until doubled in size.
Make the filling: Mix brown sugar, cinnamon, and nutmeg in a small bowl.
Roll the dough into a rectangle approximately 15×10 inches.
Spread the softened butter evenly over the dough. Sprinkle with the cinnamon-sugar mixture and optional chopped nuts.
Roll the dough tightly from the long side into a log.
Cut into 12 rolls and arrange in a greased 9×13-inch baking dish.
Cover and let rise for another 30–45 minutes.
Preheat oven to 350°F.
Bake for 25–30 minutes, until golden brown and cooked through.
Make the glaze: Beat cream cheese and butter until smooth. Add powdered sugar and vanilla, then gradually add milk until you reach a smooth, spreadable consistency.
Spread the cream cheese glaze over the warm cinnamon rolls.
Notes
For extra banana flavor, drizzle the finished rolls with a little caramel sauce and sprinkle with chopped toasted pecans.