Yes, you can absolutely use overripe bananas in baking! In fact, overripe bananas are often preferred in baking recipes because they are sweeter and have a stronger banana flavor compared to regular-ripe bananas.
When it comes to mashed up volume, overripe bananas tend to be softer and more easily mashed than regular-ripe bananas. This is because as bananas ripen, their starches convert to sugars and their texture becomes softer. The softer texture of overripe bananas makes them easier to mash, resulting in a smoother consistency when incorporated into baked goods.
In terms of measurement, it's generally recommended to use the same amount of mashed overripe bananas as regular-ripe bananas called for in a recipe. So, if a recipe asks for 1 cup of mashed regular-ripe bananas, you can use the same amount of mashed overripe bananas.
Keep in mind that overripe bananas may release more liquid when mashed, which can affect the overall moisture content of your baked goods. Adjustments to other ingredients, such as reducing the amount of liquid (e.g., milk or water) in the recipe, may be necessary to compensate for the additional moisture from the overripe bananas. Additionally, the intense sweetness of overripe bananas may also affect the overall sweetness of the baked goods, so you might want to adjust the amount of sugar in the recipe if needed.
Overall, using overripe bananas in baking is a great way to prevent food waste and add extra flavor to your treats!