Preheat the oven to 375F (190C).
NOTE: The bake time will depend on the oven, so keep an eye on the bread as it bakes. It's ready when it no longer jiggles in the centre and a toothpick comes out clean.
Peel and mash the banana in a bowl. Add the egg, vanilla extract, and sugar. Mix well.
Add the oil, milk, flour, and baking soda, and mix. Optionally, stir in some crushed walnuts or chocolate chips.
Spray and line a 10-ounce ramekin with parchment paper. Pour in the batter and tap to distribute evenly.
Bake for 25 to 30 minutes or until fully set and a toothpick comes out dry.
Let cool, dust with icing sugar, and enjoy!
