Preheat your oven to 350°F (175°C) and prepare a 9x5-inch loaf pan by greasing it lightly with oil or lining it with parchment paper.

In a large mixing bowl, whisk together one large egg, both brown and granulated sugars, liquid-state coconut oil, sour cream, and vanilla extract until smooth.

Add mashed ripe bananas to the wet mixture and stir gently until evenly incorporated.

Fold in all-purpose flour, baking powder, baking soda, and a pinch of salt until just combined, aiming for a slightly lumpy batter.

Pour about two-thirds of the banana bread batter into the prepared loaf pan, smoothing it down.

In a separate bowl, combine softened cream cheese, additional granulated sugar, and all-purpose flour. Whisk until smooth and creamy.

Pour the cream cheese filling over the banana bread batter in the pan and spread it evenly.

Pour the remaining banana bread batter over the cream cheese layer, smoothing the top out carefully.

Bake for 48 to 50 minutes, until the top is golden brown and a toothpick inserted comes out clean.

Once baked, let the bread cool in the pan for about 15 minutes before transferring it to a wire rack to cool completely.