Peel the sweet potato and cut into 1-inch (2.5cm) cubes. Place in a steamer basket over boiling water and steam for 12-15 minutes, until a fork slides through easily with no resistance.
Let the steamed sweet potato cool for about 5 minutes — it should still be warm but comfortable to handle. Blending while slightly warm gives the smoothest texture.
Add the warm sweet potato, bananas, and almond milk to a blender. Blend on high for 60-90 seconds until completely smooth and no lumps remain. Scrape down the sides halfway through if needed.
Divide the pudding evenly among 3 serving glasses or ramekins. Refrigerate for at least 1 hour until set and chilled through, or serve immediately for a warm pudding.