Overripe bananas suitable for baking will have brown or black spots covering most of the peel, feel very soft to the touch, and possess a strong, sweet aroma. The inside should still be mostly intact and not moldy.
Determining if a banana is overripe but still good for baking involves assessing several key characteristics:
Essentially, you're looking for bananas that are past their prime for eating raw but are still structurally sound and free from spoilage. The browner the better, up to a point!
If you have bananas ripening faster than you can use them, peel them, slice them, and freeze them in a single layer on a baking sheet before transferring them to a freezer bag. This prevents them from clumping together and makes them easy to grab for smoothies or baking later.