Preheat the oven to 170°C (340°F) for 10 minutes. Line a 9-inch loaf pan with parchment paper.
Peel the overripe bananas and place them in a bowl. With a fork, mash the bananas.
After that, mix in the butter and oil.
Now, add the sugar to the mixture and thoroughly combine it.
After that, fold in the eggs. Add one egg at a time, whisking well after each addition.
Next, stir in the cinnamon powder thoroughly.
Sift together the flour, baking powder, baking soda, and salt and stir them into the batter.
Using the cut and fold method, fold the dry mixture into the wet mixture. Add a small amount of milk at a time until the batter is smooth.
Now stir in the tutti frutti to the batter.
Finally, pour the batter into the prepared loaf pan and bake for 45 minutes, or until a toothpick inserted into the center comes out clean.
After that allow to cool the cake for a while and later slice it and store it in a dry and airtight container.