Cocoa Banana Muffins from The Modern Baker by Nick Malgieri

Ingredients

• 3 medium bananas, peeled and mashed with a fork to make 1½ cups
• ½ teaspoon salt
• 1 teaspoon baking soda
• 3 large eggs
• 1 cup granulated sugar
• 12 tablespoons (1½ sticks) unsalted butter, softened
• ½ cup light brown sugar
• ½ cup sour cream
• ⅔ cup alkalized (Dutch process) cocoa powder, sifted after measuring
• 1½ cups all-purpose flour (spoon flour into a dry-measure cup and level off)