Preheat the oven to 425°F and line a 12-cup muffin pan with paper liners or grease the cups; set aside.

In a small bowl, beat 4 ounces softened cream cheese with 2 tablespoons granulated sugar and 1/2 teaspoon vanilla until smooth; refrigerate briefly to firm if needed.

In a medium bowl whisk together 2 cups flour, 1 teaspoon baking soda, 1/2 teaspoon baking powder, 1/2 teaspoon salt, and 1/2 teaspoon cinnamon.

In a large bowl whisk 2 large eggs, 1/2 cup granulated sugar, 1/3 cup packed light brown sugar, 1/3 cup melted butter, 1/4 cup sour cream, 1 1/2 cups mashed ripe bananas, and 1 teaspoon vanilla until smooth.

Add the wet ingredients to the dry and fold gently with a spatula until only a few streaks of flour remain; do not overmix.

Spoon batter into muffin cups about two-thirds full; drop about 1 teaspoon of the cream cheese mixture onto the center of each and make one or two shallow swirls with a skewer; top with a thin banana slice or pecans if using.

Bake at 425°F for 5 minutes, then reduce oven temperature to 350°F and bake 13–15 minutes more, or until tops are set and a toothpick away from the cream cheese swirl comes out with a few moist crumbs but not wet batter.

Let muffins rest in the pan for 5 minutes, then transfer to a wire rack to cool; serve warm or at room temperature.