Preheat the oven to 180°C (350°F) gas mark 4.
Coat the cake tins with nonstick spray and line the bottom with parchment paper. (See Note 1).
In a medium bowl whisk the flour, baking soda, and salt.
Using an electric whisk, beat the sugar, butter, and brown sugar in a large bowl until light and fluffy, for about 3 minutes.
Add the vanilla extract and the eggs one at a time, beating to blend between additions and occasionally scraping down sides and bottom of bowl.
Add dry ingredients and beat on low speed just to blend.
Add the bananas and sour cream and gently beat just to blend.
Fold in the mini chocolate chips.
Divide batter evenly among both tins.
Bake the cakes for about 35 minutes in the preheated oven.
Transfer the cakes to wire racks and let the cakes cool down for 10 minutes.
Invert the cakes onto the racks and peel off the parchment paper and let cool completely.
