From my story, Crumbs and the Single Girl
1 stick (1/2 cup) butter or butter substitute (i.e., Earth Balance)
2/3 cup granulated sugar
1/3 cup brown sugar
2 large eggs
2 tbsp sour cream or plain yogurt
¼ tsp instant espresso powder
1 tsp cocoa powder
2 tsp vanilla extract
1 ¾ plus 2 tbsp all purpose flour
2 tsp baking powder
¼ tsp baking soda
½ tsp salt
3 ripe bananas, mashed with a fork
½ cup walnuts, roughly chopped
Prepare a 1 pound (7 ½” x 3 ½” x 3”) loaf pan by greasing and flouring it.
Preheat your oven to 350˚F.
In the bowl of a stand mixer, mix together on medium speed the butter and sugars until the butter has lightened in color and the mixture is fluffy, about three minutes.
Add the eggs, one at a time, then the yogurt, continuing to mix until well combined.
Add the cocoa powder, instant espresso powder, and vanilla extract, and mix until combined.
Stop the mixer. Using a rubber scraper, scrape down the sides of the bowl. Add the flour, baking powder, baking soda, and salt, Mix on low until just combined.
Add the mashed banana, and continue mixing on low just until it has been absorbed into the batter. Add the crushed walnuts and mix for just a few seconds until they are evenly distributed into the batter.
Transfer to the prepared loaf pan. Bake in the preheated oven for 50 to 55 minutes, or until a toothpick inserted into the center comes out clean.
Cool in the pan for about 10 minutes, then remove from the pan and cool on a rack for several hours, or refrigerate overnight.(The cake is better the next day.)