01 - In a large mixing bowl, stir together warm milk and active dry yeast. Let rest for 5 minutes until the surface becomes foamy. Add melted butter, mashed bananas, granulated sugar, egg, and salt. Mix until well combined, then gradually incorporate the flour, mixing until a rough dough forms. Knead for 8 to 10 minutes by hand or using a mixer with a dough hook, until the dough is smooth and elastic.
02 - Place the kneaded dough in a lightly greased bowl. Cover with a clean towel or plastic wrap and set in a warm location for 1 hour, or until the dough has doubled in volume.
03 - In a small bowl, blend together brown sugar, ground cinnamon, and ground nutmeg until well combined.
04 - Punch down the risen dough and transfer it to a floured work surface. Roll the dough into a 16 by 12-inch rectangle. Evenly spread softened butter across the surface, then sprinkle the cinnamon sugar filling uniformly over the dough.
05 - Tightly roll up the dough from the long edge to create a log. Slice evenly into 12 portions.
06 - Arrange the sliced rolls, cut side up, in a greased 9 by 13-inch baking dish. Cover and let rise in a warm location for 30 to 45 minutes, until puffy.
07 - Preheat the oven to 350°F. Bake the rolls for 22 to 25 minutes, until the tops are golden brown.
08 - While the rolls bake, use a hand mixer or stand mixer to beat together softened cream cheese, softened butter, powdered sugar, milk, and vanilla extract until smooth and creamy.
09 - Allow baked rolls to cool in the pan for 10 minutes. Generously spread the cream cheese icing over warm rolls and serve immediately.