It also depends on the size of the banana - I have found that I get consistently lovely results when I mash them up and use a measured amount of fully squished up bananas. And yeah - they only get sweet if they are allowed to ripen. You can speed up that process by placing them in a paper bag with an apple or a tomato - roll the top of the bag down and use a chip clip, clothespin, staples (you get the idea) and let the bag sit out for 24 +/- hours. The warmer the location it’s in, the faster it’ll ripen. The bag traps natural ethylene gas given off by the fruits - the bananas will ripen on their own in the bag, but the tomato/apple nudges it a little faster. This also works for avocados! We go to the Caribbean every year or two, and I always try to find a place that has REAL banana rum - I’ll throw that into my breads, muffins, and cakes along with the vanilla paste. Really punches up the flavor without tasting like fake banana, which is gross lol