Preheat the oven to 180°C.
Line two muffin tins with paper cases or put 12 silicon muffin cups on a baking sheet.
In a large bowl, mix together the flour, baking powder, oats and cinnamon, if used.
In another bowl, mash the bananas, the add the eggs and the oil. Fold in the dry mixture and combine until you get a thick batter. Add the fruit purée and more oats, if the batter is too wet.
Fold in the nuts, dates & raisins.
Transfer the batter into the muffin cases.
Bake the muffins for about 25 minutes, until light brown and an inserted skewer comes out clean.
Cool them for a few minutes in the tin or silicon cases, then transfer them onto a wire rack to cool completely.