It is merely a ripe banana (usually more than 1) that I have cut the top off of, then placed on a cookie sheet type of baking apparatus. I then roast it in the oven at a pre-heated 350 degrees temperature, and let blacken for about 15 mns or so, until they look like this:
This, my friends, make the sweetness and taste of the bananas basically explode and triple. The bananas inside will have yellowed, and the opening will have oozed the water, leaving behind the intense flavor. So simple, yet so effective. I dont think I make any sort of banana recipe that doesnt involve eating raw banana in its simple form without roasting them first.
In case you were interested, here is a video that shows a banana bread made with roasted bananas. Along with hick banjo music and a heavily bearded chef. I have not tried the recipe, but it amuses me to post the video anyways. Happy baking!