Step 1: Activate the yeast. In a small bowl, pour ½ cup of warm milk (110°F/43°C) and sprinkle 2¼ teaspoons (one packet) of active dry yeast over the surface. Let this mixture sit undisturbed for 5 to 10 minutes. When the yeast is fully activated, the milk will be foamy on top, signaling that it’s ready to leaven your dough.
Step 2: Combine mashed bananas and wet ingredients. In a large mixing bowl, mash 1 cup of ripe bananas (about 2–3 medium bananas) until smooth. Add ¼ cup of granulated sugar, ¼ cup of melted butter, 1 large beaten egg, and ½ teaspoon of salt. Stir until the ingredients are well incorporated, then pour in the foamy yeast mixture. Mix gently until the liquid is absorbed and the bowl holds a loose, sticky batter.
Step 3: Incorporate the flour. Gradually stir in 3 cups of all-purpose flour, one cup at a time. After each addition, mix until the dough begins to pull away from the sides of the bowl. If the dough remains overly wet, add up to an additional ½ cup of flour—no more—to achieve a slightly tacky but manageable dough.
Step 4: Knead until smooth and elastic. Turn the dough onto a lightly floured surface. Knead by hand for 6 to 8 minutes, adding just enough flour to prevent sticking. You’re aiming for a smooth, elastic ball that springs back when pressed. If you prefer using a stand mixer, knead on medium speed with the dough hook attachment for the same amount of time.
Step 5: Roll out the dough. Turn the risen dough onto a lightly floured surface. Using a rolling pin, press and roll the dough into a rectangle roughly 12×16 inches and about ¼-inch thick. Aim for straight edges so that when you slice, each roll is uniform in size and shape.
Step 6: Spread the cinnamon filling. Evenly spread 3 tablespoons of softened butter over the dough, leaving a ½-inch border along the top edge. In a small bowl, mix ½ cup of brown sugar with 1 tablespoon of ground cinnamon. Sprinkle this cinnamon–sugar mixture over the butter, pressing lightly with your fingers or the back of a spoon so it adheres.
Step 7: Shape and cut into rolls. Starting at the long edge nearest you, roll the dough up tightly into a log. Pinch the seam closed to prevent it opening. Measure its length and use a sharp knife or unflavored dental floss to cut twelve equal 1½-inch slices. Transfer each slice, cut side up, into a greased 9×13-inch baking dish, leaving a small gap between them to allow for expansion.
Step 8: Second rise and preheat. Cover the pan loosely with greased plastic wrap or a clean kitchen towel. Let the rolls rise in a warm, draft-free spot for 30–45 minutes, until puffy and nearly doubled. While they rise, preheat your oven to 350°F (175°C). This second proof ensures a light, tender interior.
Step 9: Bake until golden brown. Remove the cover and place the pan on the center rack. Bake for 20–25 minutes, until the rolls are a deep golden color and the centers spring back gently when pressed. If the edges brown too quickly, tent the pan lightly with foil for the last 5 minutes.
Step 10: Prepare the cream-cheese icing. While the rolls cool slightly (5–10 minutes), beat together 4 ounces of softened cream cheese, 2 tablespoons of softened butter, 1 cup of powdered sugar, and ½ teaspoon of vanilla extract. Add 1–2 tablespoons of milk, a teaspoon at a time, until the icing reaches a spreadable yet still thick consistency.
Step 11: Ice and serve. Spread or drizzle the cream-cheese icing over the warm rolls, letting it melt into the swirls. Serve immediately for the best combination of gooey center and tender dough.