Preheat your oven to 350°F (175°C). Lightly coat a 9×5-inch loaf pan with floured cooking spray, or grease and flour it thoroughly to prevent sticking. Set aside.
Make the Banana Bread
In a large mixing bowl, whisk together the egg, both sugars, coconut oil, sour cream, and vanilla until everything is smooth and fully combined.
Add the bananas and stir to incorporate.
Add 1 cup of flour, baking powder, baking soda, and a pinch of salt if desired. Gently fold the mixture with a spatula or stir lightly with a spoon until just combined. Be careful not to overmix, then set aside.
Pour about two-thirds of the batter into the prepared loaf pan. Use a spatula to spread it evenly, smoothing the top and pushing the batter gently into the corners and along the sides. Set aside.
Make the Cream Cheese Filling
In a large bowl, add all ingredients and whisk to combine. Alternatively, mix with a hand mixer.
Evenly pour the filling mixture over the bread batter. Use a spatula to spread it gently, smoothing the top and guiding it into the corners and sides of the pan as needed.
Spoon the remaining batter over the cream cheese layer, spreading it carefully so you don’t disturb the filling. Smooth the top lightly with a spatula, gently pushing the batter into the corners and along the sides of the pan.
Bake for 48 to 50 minutes, or until the top is golden, domed, and the center looks set. Insert a toothpick into the middle—if it comes out clean or with just a few moist crumbs (but no wet batter), it’s done. Keep in mind that the cream cheese layer stays soft, so the toothpick test may not be completely accurate.
Let the bread cool in the pan for about 15 minutes, then carefully turn it out onto a wire rack. Allow it to cool completely before slicing and serving for the best texture and clean slices.
