Step 1: Prepare Your Banana Syrup. In a small saucepan, combine the mashed overripe banana, brown sugar, a splash of water, ground cinnamon, and a tiny pinch of ground nutmeg. Heat over medium-low heat, stirring frequently, until the sugar has dissolved and the mixture is warm and fragrant, about 3-5 minutes.
Step 2: Brew Your Coffee. Prepare a double shot of espresso or brew about 4-6 ounces of very strong coffee. The strength of your coffee is important here; it needs to be robust enough to hold its own against the sweet and creamy banana flavors.
Step 3: Warm and Froth Your Milk. While your coffee is brewing, warm your milk of choice. You can do this on the stovetop over medium heat (don’t let it boil!) or in the microwave. Once warm, froth the milk using a steam wand, an electric frother, or by vigorously shaking it in a sealed jar until foamy.
Step 4: Assemble Your Latte. Pour the prepared banana syrup into the bottom of your favorite mug. Add the freshly brewed espresso or strong coffee. Stir gently to combine the banana syrup and coffee.
Step 5: Top and Garnish. Slowly pour the frothed milk over the coffee-banana mixture, holding back the foam with a spoon initially, then spooning it on top. For the perfect finishing touch, sprinkle a little extra cinnamon or a tiny dash of nutmeg over the foam. A thin slice of fresh banana or a sprinkle of chopped walnuts can also make for a beautiful and tasty garnish. Enjoy immediately!