Sweet and Moist Banana Upside-Down Cake - Quickie Treats

Ingredients

• ⅔ cup packed brown sugar
• 4 ½ tablespoons unsalted butter, cut into small pieces
• 3 medium bananas, sliced 1/4-inch thick
• 1 ¾ cups all-purpose flour
• 1 ½ teaspoons baking powder
• 1 teaspoon baking soda
• ½ teaspoon ground cinnamon
• 1 pinch salt
• ¾ cup white sugar
• ⅓ cup unsalted butter, softened
• 2 large eggs
• 1 ½ teaspoons vanilla extract
• 2 medium overripe bananas, mashed
• ⅓ cup sour cream