In a bowl, sift together the all-purpose flour, cornstarch, coconut flour, and baking powder. Add and mix in the nutmeg and cinnamon.
In another bowl, mash the bananas and beat together with the brown sugar, granulated sugar, and vanilla extract.
Add the beaten eggs, melted butter, and plain yogurt to the banana mixture and mix well.

Add the banana mixture, golden raisins, and walnuts to the flour mixture and mix until well combined.
Grease a loaf pan and spread the batter evenly in the pan.
Preheat the oven to 350°F (176°C).

FINISHING
Remove the banana bread from the pan while it's still warm. Turn it out and let it cool completely.
Spread the cream cheese frosting over the top and sides of the bread. Use a fork to make lines on the frosting. Decorate the top with golden raisins and walnut halves. If you like, you can make a simple syrup for the walnuts to give them a shiny finish.