Preheat your oven to 350°F. Line a 9X5inch metal baking pan with parchment paper, making sure it goes up and over the long sides.
In a large mixing bowl, mash or beat the very overripe bananas until smooth.
Add the vegetable oil, vanilla extract, melted and cooled butter, granulated sugar, dark brown sugar, sour cream, and eggs to the mashed bananas. Mix until well combined.
In a separate bowl, whisk together the all-purpose flour, baking soda, kosher salt, and cinnamon until evenly mixed.
Gradually add the dry ingredients to the wet mixture, whisking gently until just combined. Be careful not to over mix.
Pour the batter into the prepared 9x5-inch metal baking pan, smoothing the top with a spatula. Top with the streusel, making sure it is evenly distributed over the top.
Position it on the center rack of the oven to ensure even baking, avoiding placement too close to the top or bottom. Bake for 55-60 minutes, or until a toothpick inserted into the center comes out clean.If it's getting too brown place a piece of foil on top to prevent it from getting too dark.
Allow the banana bread to cool in the pan for about 10 minutes, then transfer it to a wire rack to cool completely.