Apple Cider Whoopie Pies with Caramel and Cream Cheese Fillings

Ingredients

• 2 cups apple cider, reduced to 1/4 cup
• 6 tablespoons unsalted butter, room temperature
• 1 3/4 cups all-purpose flour
• 1/2 teaspoon fine sea salt
• 1 teaspoon baking powder
• 1/4 teaspoon baking soda
• 1 1/2 teaspoons ground cinnamon
• 1/4 teaspoon ground ginger
• 1/2 teaspoon ground nutmeg
• 1/2 cup granulated sugar
• 1/4 cup plus 2 teaspoons light or dark brown sugar, packed
• 1/4 cup apple butter or unsweetened applesauce
• 2 large eggs
• 1/4 teaspoon pure vanilla extract
• 3 tablespoons unsalted butter, melted
• 1/4 cup granulated sugar
• 1/2 teaspoon ground cinnamon
• 1/2 cup unsalted butter, room temperature
• 1 1/4 to 1 1/2 cups powdered sugar, sifted, plus more if needed
• 2 tablespoons plus 2 teaspoons bourbon caramel sauce, cooled to room temperature
• 1 pinch fine sea salt
• 4 1/2 ounces cream cheese, room temperature
• 3 tablespoons unsalted butter, room temperature
• 2 tablespoons light or dark brown sugar
• 2 cups powdered sugar, sifted, plus more if needed
• 1/2 teaspoon pure vanilla extract
• 2 tablespoons unsalted butter, melted