Prep a pan – 8-inch round cake pan or 8½ x 4½-inch loaf pan. Butter the bottom, sides, and edges of a pan. Pour in some flour and shake it around until the pan is evenly coated, then tap out any excess flour. You can also place parchment at the bottom for easy release later.

Preheat the oven to 180 degrees Celsius.

Sift the powdered sugar, flour, baking soda, nutmeg, salt, and baking powder in a large bowl.

Whisk the eggs in a separate large bowl. Mix in the mashed bananas. Pour the egg mixture over the dry ingredients and whisk until well combined. Stir in the melted butter.

Pour the batter into the prepared pan. Bake until the cake is golden brown, about 1 hour.

Let the cake cool in the pan. Unmold and serve.