The key ingredient are extremely ripe bananas that you'll need to freeze in advance.
We use this extremely rich, gooey vanilla extract that we received as a gift from my mother-in-law. This gives our frozen yoghurt little specs of vanilla bean which I personally think make it look, and therefore taste even better.
Here's the recipe!
Homemade Banana Frozen Yoghurt
by Tarts and Crafts
3 extremely ripe frozen bananas
1 cup yoghurt
1 tbsp vanilla extract
Peel the frozen bananas (this can be tough to do, so we usually let the bananas thaw out for 5 minutes before we start peeling them), break them up in small pieces with your hands and place them in the food processor. Add the yoghurt and vanilla extract. Blend them all in the processor for 1 minute until smooth. Serve immediately. Enjoy!