Preheat oven to 350°F. Grease a 9-inch cake pan.
Whisk flour, baking soda, baking powder, salt, cinnamon, and nutmeg.
Cream butter and sugars; add eggs, vanilla, and bananas. Taste and adjust the sweetness.
Mix in half the dry ingredients, sour cream, then the remaining dry ingredients.
Bake for 30–35 minutes until a toothpick is clean. Cool for 10 minutes, then transfer to a rack.
Serve on a white ceramic cake stand with powdered sugar, bananas, cream, and coffee.