Combine milk, sliced banana, and empty vanilla bean pod in 3-quart stainless steel saucier and bring to simmer over medium heat, stirring from time to time with flexible spatula to prevent scorching along bottom. When dairy comes to a simmer, remove from heat, cover and let cool to room temperature, about 4 hours. Proceed to next step, or refrigerate up to 24 hours to extract stronger banana flavor. The exact timing will depend on both personal preference and convenience.
