Banana Cupcakes With Peanut Butter Frosting

Ingredients

• 1 1/4 cups all purpose flour
• 1 1/2 teaspoons baking powder
• 1/2 teaspoon baking soda
• 1/4 teaspoon salt
• 2 very ripe large bananas, peeled
• 1/2 cup sour cream
• 1 1/2 teaspoons vanilla extract
• 3/4 cup sugar
• 1/2 cup (1 stick) unsalted butter, room temperature
• 1 large egg
• 1 large egg yolk
• 1 1/2 cups powdered sugar
• 1 8-ounce package cream cheese, room temperature
• 1/2 cup (1 stick) unsalted butter, room temperature
• 1/2 cup smooth peanut butter (do not use old-fashioned or freshly ground)
• chopped lightly salted roasted peanuts (optional)