Split the Skin
Look for plantains that are very soft and range from nearly black to all black. Start by splitting the skin along one side with a sharp knife.
Peel away the skin, trying to keep the plantain intact.
Cut a deep slit in the plantain lengthwise, making sure not to cut all the way through.
Pull the plantain open like a hot dog bun.
Spread the Cream
Fill the slit with cream. Colombian cream is thick like British double cream, but with a slight tang. Crème fraîche will work well in its place.
Sprinkle the cream with sugar.
Then top it with ground cinnamon.
Roast and Serve
Roast it in a 350°F oven until lightly caramelized and the plantain has absorbed the cream, giving it a rich, custard-like texture.