Set a pot of water to boil
Cut both ends off of the bananas
Make a cut lengthwise from top to bottom (you are trying to make an opening between the skin and the banana, not actually slice it)
Put in the pot of boiling water. It’s a good idea to tip a bit of acid in the pot, like a wedge of lemon or a tablespoon or so of apple cider vinegar, to prevent staining your pot.
Once the bananas are tender and the skin will come off easily (approximately 15 minutes), remove from pot.
Peel off the remaining skin.
Mash with butter and sea salt or other desired seasonings.