Prep the pan and oven: Preheat the oven to 350°F (175°C). Generously grease and flour a 10–12 cup Bundt pan, making sure to coat every ridge. Tap out any excess flour.

Mash the bananas: In a bowl, mash the ripe bananas until mostly smooth with a few small lumps. Stir in the sour cream and vanilla. Set aside.

Whisk dry ingredients: In a separate bowl, whisk flour, baking soda, baking powder, salt, cinnamon, and nutmeg (if using).

Cream butter and sugars: In a large mixing bowl, beat the softened butter with granulated sugar and brown sugar until light and fluffy, about 2–3 minutes. Beat in the oil.

Add the eggs: Add eggs one at a time, mixing well after each addition and scraping down the bowl as needed.

Combine wet and dry: Add half of the dry mixture to the butter mixture, then mix on low. Add the banana mixture, then the remaining dry mixture. Mix just until no dry streaks remain. Do not overmix.

Fold in nuts (optional): Gently fold in chopped walnuts or pecans.

Fill the pan: Spoon the batter into the prepared Bundt pan and smooth the top. Tap the pan firmly on the counter to release air bubbles.

Bake: Bake for 50–60 minutes, or until a toothpick inserted near the center comes out clean or with a few moist crumbs. The top should be golden and spring back to the touch.

Cool properly: Let the cake cool in the pan for 10–15 minutes, then carefully turn out onto a wire rack. Cool completely before frosting.

Make the frosting: Beat cream cheese and butter until creamy and smooth. Add powdered sugar, cinnamon, vanilla, and a pinch of salt. Beat until fluffy, adding milk or cream 1 tablespoon at a time until it’s thick yet pourable.

Frost: Drizzle or spread the frosting over the cooled cake, letting it cascade down the sides. Sprinkle with a pinch of cinnamon or chopped nuts if you like.

Slice and enjoy: Let the frosting set for 10–15 minutes before slicing for cleaner cuts.