Preheat your oven to 350°F (175°C) and line a 9×5-inch loaf pan with parchment paper, leaving some overhang for easy removal.
In a medium bowl, beat the softened cream cheese until smooth and fluffy (approximately 1 minute). Add ¼ cup sugar, 1 egg, and 1 teaspoon vanilla extract. Beat until completely smooth and no lumps remain. Set aside.
In a large bowl, mash the ripe bananas until nearly smooth with some small chunks remaining. Whisk in the eggs, melted butter, both sugars, and vanilla until well combined.
In a separate bowl, whisk together flour, baking soda, salt, cinnamon, and nutmeg.
Gently fold the dry ingredients into the banana mixture until just combined. If using nuts, fold them in now.
Pour two-thirds of the banana bread batter into your prepared loaf pan. Spoon the cream cheese mixture over the batter. Add the remaining banana bread batter on top.
Use a knife or skewer to gently swirl the batters together, creating a marbled effect with 8-10 figure-eight motions.
Bake for 60-65 minutes, or until a toothpick inserted in the center comes out with a few moist crumbs but no wet batter. If the top browns too quickly, cover loosely with aluminum foil after 40 minutes.
Allow the bread to cool in the pan for 15-20 minutes before using the parchment paper to lift it out. Cool completely on a wire rack before slicing.