Banana Nut Cheerios Cupcakes - Cupcake Fanatic

Ingredients

• 3/4 cup unsalted butter, at room temperature
• 3 eggs, at room temperature
• 2 cups all-purpose flour
• 1 1/2 teaspoons baking powder
• 3/4 teaspoon salt
• 1/4 teaspoon baking soda
• 1 teaspoon cinnamon
• 1/2 mashed overripe banana (1 large)
• 3/4 cup buttermilk
• 1 teaspoon vanilla extract
• 1 scant cup sugar
• 2/3 cup powdered sugar
• 1/2 cup creamy peanut butter
• 2 tablespoons unsalted butter, at room temperature
• 1/4 teaspoon vanilla extract
• 1 1/2 cups crushed peanut butter Cheerios cereal
• 8 ounces egg whites (from a carton is fine)
• 12 ounces sugar
• 1 1/4 cups unsalted butter, at room temperature
• 3 tablespoons caramel sauce