Once that's done, add the vanilla, oil and yoghurt, then beat again briefly until homogeneous. Then gradually add the flour until you get a smooth and thick mixture.
Mash the bananas in a bowl with a fork and add them to the mixture, while stirring carefully with the fork to mix well. Turn the oven on to heat up to 356°F (180 °C) and in the meantime, distribute the mixture into muffin forms.
I used a Teflon muffin tray and paper cups. Fill them up 3/4 of the way up, so there's room for them to swell during baking. My muffin tray yielded 16 muffins but if yours are smaller or larger, the number will vary.
Bake about 25 min. but do keep an eye on them. Check to see if they're ready with a toothpick. For a better bake, put them on the lower element.