I promise you this cake is worth the wait! BUT if you really need to get things going, make sure your bananas are in a warm area in a paper bag for a day or two. I have seen 'hacks' for cooking your bananas to make them ripen faster but this won't give you the same banana taste! You could also try mashing the bananas with one of the egg yolks in the recipe and letting it sit for 30 minute, this allows the enzymes from the egg to 'ripen' the bananas faster.