Kue Pie Whoopie Coklat

Bahan-bahan (12 porsi)

• 1 (15,25 ons) kotak campuran kue fudge coklat
• 1 (3.9-ounce) box instant chocolate fudge pudding mix
• ¾ cup air
• ¾ cup vegetable or canola oil
• 4 large large eggs
• 1 cup sour cream, (or Greek yogurt)
• 1 teaspoon ekstrak vanila
• 10 tablespoons unsalted butter, (room temperature)
• 1 (7-ounce) jar marshmallow creme
• pinch salt
• 1 ½ teaspoon ekstrak vanila
• 2 cups powdered sugar, (divided)
• ½ cup chocolate chips, (I used milk chocolate)
• 3 tablespoons krim kocok