Preheat Oven: Preheat the oven to 356ºF (180ºC) fan-forced.
Tin Prep: Grease an 8-inch round baking pan with butter and line with parchment paper. Note: For non-stick pans, line the base with parchment paper and grease just the sides with butter and dust with flour for smooth cake sides. Set aside.
Mash Bananas: In a large mixing bowl, mash the bananas.
Add Wet Ingredients: Whisk in the eggs, olive oil, milk, and vanilla until well combined.
Whisk in Sugars: Add both granulated and brown sugar and whisk until well combined.
Add Dry Ingredients: Sift in the flour, baking powder, baking soda, and cinnamon. Then add the salt. Mix until incorporated, ensuring not to over-mix. Either whisk or rubber spatula will work here.
Pour Batter Into Tin: Pour the batter into the lined tin, smoothing the top.
Bake: Bake for 50-55 minutes or until a toothpick inserted into the middle comes out clean or just with a few moist crumbs.
Cool: Remove from the oven and let the cake cool in the tin for 15 minutes. Transfer the cake to a wire rack to cool completely before adding the frosting.