Baking and frying are two common ways to cook plantains. Food.com and Craftsy.com both offer a wide variety of methods for cooking and preparing plantains.
To make oven-baked sweet plantains, preheat the oven to 450 F, and coat a cookie sheet with cooking spray. Lay 1/2-inch-thick slices of plantains in a single layer on the sheet before spraying another coat of cooking spray. While baking, occasionally turn the slices, and allow the plantains to cook for about 10 to 15 minutes. Remove the plantains, and allow them to cool before eating.
For the frying method from Craftsy.com, begin by cutting the plantains into 1/4-inch-thick slices. Pour enough vegetable oil into a frying pan to coat the entire bottom. Place over medium heat, and add in the plantains, frying them for one and a half to two minutes or until they become crispy. Flip the plantains with a spatula or tongs to allow the other side to fry for about another minute. Remove the plantains from the pan, and set them aside to cool.