If you need a ripe banana today, Giada De Laurentiis has you covered. She shared this trick to ripen bananas fast on her Giadzy blog. Place the individual banana (peel intact) on a foil-lined, rimmed sheet tray. Bake in a 300°F oven for 15-30 minutes until peel turns brown. Alternatively, you can microwave the banana in its peel for 30 seconds to two minutes (be sure to poke holes around the peel first!). But the best way to ripen a banana takes a little longer. If you can wait the 24-48 hours, try the paper bag method. Place the bunch of bananas in a paper bag and seal it. Bananas emit ethylene gas, which aids in the ripening process. By trapping the gas in the bag, you speed the process up. Now that you have ripe bananas, try mashing them into a microwaveable mug oatmeal or banana bread.