Preheat your oven to 350°F (175°C). Grease and flour a bundt pan or a 9x13" cake pan. In a small bowl, mash your bananas until smooth. Set aside. In a large mixing bowl, combine Yellow cake mix, Banana pudding mix, Eggs, Vegetable oil, Mashed bananas, Sour cream, Vanilla extract, and Cinnamon (if using). Mix using a hand or stand mixer on medium speed for 2–3 minutes until the batter is smooth and well combined. 👉 Fold in chopped nuts if using.

Pour the batter into your prepared pan and smooth the top. Bake for 50–60 minutes (for bundt) or 35–40 minutes (for 9x13”), or until a toothpick inserted in the center comes out clean. Let the cake cool in the pan for 10–15 minutes. Turn it out onto a wire rack to cool completely before slicing.