Marbled Banana Bread - Once Upon a Chef

Ingredients

• 1¾ cups all purpose flour, spooned into measuring cup and leveled-off
• ¾ teaspoon baking soda
• ¾ teaspoon salt
• 1 cup sugar
• 1 stick (½ cup) unsalted butter, softened
• 2 large eggs
• 1 cup mashed very ripe bananas, from 2-3 bananas
• ½ cup sour cream
• 1 teaspoon vanilla extract
• 3 ounces semisweet chocolate, chopped (a heaping ½ cup)
• 2 teaspoons natural unsweetened cocoa powder, such as Hershey's