Preheat the oven to 350 F. Line a muffin/cupcake tray with liners and keep it ready.

In a mixing bowl, mash the banana using a fork followed by oil, vanilla extract, milk and brown sugar.Mix well using a whisk.

Sieve the dry ingredients like flour, oats, baking powder, pinch of salt and baking soda to the wet banana mixture. Mix everything well together.

Add chopped walnuts,cranberries and raisins. Gently fold the mixture so that walnuts and dry fruits are nicely incorporated.

Scoop this batter into the pre-lined muffin tray. Fill each muffin liner till 3/4th full. Top it with some walnuts (optional).

Bake at 350 for 25-30 mins or until done i.e. toothpick inserted in the center of muffin comes out clean without an batter stuck on it.

Let them cool in the tray for 10 mins and then transfer on to a cooling rack. Serve or store in airtight container for upto 3-4 days. Or freeze upto 2 weeks for later use.

NOTES:

Don't over mix the batter as that may result in hard muffins.
The more ripe the bananas are the better and sweeter they are. Mine had almost black skin on them.
The sweetness of banana can vary so taste the mixture before adding sugar and adjust to your taste. For me 1/2 cup sugar worked perfect.
Addition of nuts gives the nuts a nice crunch. Any nuts of choice can be used
You can replace banana with about any fruit puree.