This recipe made the rounds on the internet a couple years ago but I never got around to testing it, until today. The claims are true! You really can make creamy and delicious ice cream out of just bananas with the added bonus of it being good for you. Technically this isn't one ingredient since (as suggested by the internet) I added a couple other things to make it even better. But the base is just made out of frozen bananas and is delicious as is. Soren helped me make it and it was a fun little activity for him and he got to eat ice cream at 10 AM. You can go to The Kitchn to see the recipe with step by step photos and instructions.
One Ingredient Ice Cream
From The Kitchn
2 large ripe bananas, peeled and frozen
2 Tbs peanut butter
splash of vanilla
Break the bananas into pieces and put into a food processor or blender and blend on high. Initially they will look crumbly and the mixture will probably get stuck a lot so keep scraping down the bowl. As you keep blending, you'll see the mixture start to turn creamy. Add the peanut butter and vanilla, or anything else you'd like to add it. The ice cream will be the texture of soft-serve, but if you freeze in an air-tight container it will get hard more like regular ice cream.