Have all ingredients at room tmperature, 68┬░ to 70┬░F.
Preheat the oven to 350┬░F. Grease and flour a 9-inch springform pan or line the bottom with wax or parchment paper.
Combine in a food processor and process briefly just until blended:
2 large, ripe bananas
2 tablespoons sour cream
Add and process until well combined:
2 large eggs
2 teaspoons grated lemon zest
1 1/2 teaspoons vanilla
In a large bowl, beat on low speed for 30 seconds:
2 cups cake flour
3/4 cup plus 2 tablespoons sugar
1 teaspoon baking soda
3/4 teaspoon baking powder
1/2 teaspoon salt
Add half of the banana mixture along with:
10 tablespoons butter, softened
Beat on low speed just until the dry ingredients are moistened. Increase the speed to medium and beat for 1 1/2 minutes, scraping the sides of the bowl as necessary. Gradually add the remaining banana mixture in 2 batches, beating for 20 seconds after each addition. Scrape the batter into the pan and spread evenly. Bake until a toothpick inserted into the center comes out clean and the cake springs back when lightly pressed, 30 to 40 minutes. Let cool in the pan on a rack for 10 minutes. Slide a thin knife around the cake to detach it from the pan; remove the pan side. Let cool on the rack. Dust with:
