Preheat the oven to 350 degrees. Coat one bundt pan or two loaf pans with nonstick cooking spray.
In a large bowl, combine the bananas, eggs, and oil. Mix until fully combined. Stir in cake mix and mix well, Fold in pecans, if using.
Pour batter into prepared pan(s) and bake in preheated oven. Bake the bundt cake pan for 40-45 minutes or the loaf pans for 30-35 minutes. The bread is done when a toothpick inserted in the center comes out clean. Cool in pan for 10 minutes before transferring to a wire rack to cool completely.
For the cream cheese glaze: Add the cream cheese and butter to to a microwaveable safe bowl. Microwave, in 20 second intervals, stirring in between each, until the mixture is easily mixed. Stir in the vanilla and then, working in bathes if needed, the powdered sugar. The mixture should be pourable. Pour over cooled bread.