Place bananas on a rimmed baking sheet, spaced equally apart.
Bake for 20-30 minutes, or until the peel has turned black.
Remove from the oven and let cool.
Cut the peel open and remove the banana. Mash and use as directed by recipe.
Notes
While you're softening your butter for baking, you can prep your under-ripe bananas to be ready to bake!
In order for bananas to be used in baking, such as recipes like breads and cookies, they need to be ripened so that the natural sugars provide sweetness to the recipe. When bananas haven’t reached the ripe stage, this sweetness is lacking. This is a quick and easy way to speed up that process, unlike some other techniques that require 24 hour or even a couple of days.
This isn’t a process that can be done if you are looking to eat the banana or use it sliced in a dessert. After baking, the texture is very soft and is only suitable for recipes that are using it mashed and mixed into a batter or dough.
I had my doubts about how sweet these bananas would become, as they are pretty firm and green still. But, after baking, they were perfect in the banana bread.
4 ripe bananas will yield about 2-3 cups of mashed, depending on the size of your bananas.