A banana is ripe enough for baking when it is yellow, speckled with dark brown spots, but still holds its shape and isn't overly "mushy." The more brown speckles, the riper the bananas. To speed up the ripening process, Place bananas in a brown paper bag and close the top. If you have an apple, slice that and place it in the bag as well. The ethylene gas will ripen your fruit within a day or so.