Spray your donut pans with non-stick spray or grease with butter (trust me, they will stick otherwise!). Preheat the oven to 350 F.
In a medium bowl, mash up your bananas and add the nut butter, eggs, vanilla, cinnamon, and salt. Stir together (you can use a hand mixer too, but you don't need it).
Once the oven is hot, add the apple cider vinegar and baking soda to your mixture and stir together.
Immediately spoon the batter into the donut pans. I basically filled just below or right at the top, and it seemed the right amount.
Bake for 8-12 minutes (they may need a bit more time if the bananas were extra wet). They should feel baked and glossy on top and not squishy or wet-looking, but try not to over-bake (they'll be really dry).
Remove from the oven and cool for 15-20 minutes, then gently remove from the donut pans. A silicone spatula was the easiest way to do this without damaging the pans.
In a small bowl (fairly shallow if possible, and with room to dip the donuts by hand), stir together the coconut oil, chocolate chips, and sea salt over low heat or in the microwave.
Dip the cooled donuts into the glaze and allow to set before serving.