In a glass or jar (a 16-ounce capacity allows room to stir) mix the groats, chia seeds, cinnamon, and salt. You can really just mix everything together at once, but I think it is easier to mix all the dry ingredients and proceed accordingly. (Most of the packaged groats I have purchased do not require rinsing. When I have bought them in bulk, I have noticed there can be a chalky coating. If you rub the groats and notice this, the taste will be improved by a quick rinse. In this case, drain thoroughly.)
Roughly chop the banana into the glass. With a fork, thoroughly mash it against the side of the glass, and stir it into the dry ingredients. Add the pumpkin, maple syrup, and vanilla, and stir to combine. Stir in the milk, and then cover and refrigerate overnight.
Stir well before eating to evenly distribute the groats. Sprinkle with desired toppings–my latest favorite is a tablespoon each of raisins and toasted, slivered almonds–and enjoy.