Red Velvet Whoopie Pies

Ingredients

• 3/4 cup butter, softened
• 1 cup sugar
• 2 large eggs, room temperature
• 1/2 cup sour cream
• 1 tablespoon red food coloring
• 1-1/2 teaspoons white vinegar
• 1 teaspoon clear vanilla extract
• 2-1/4 cups all-purpose flour
• 1/4 cup baking cocoa
• 2 teaspoons baking powder
• 1/2 teaspoon salt
• 1/4 teaspoon baking soda
• 2 ounces semisweet chocolate, melted and cooled
• FILLING:
• 1 package (8 ounces) cream cheese, softened
• 1/2 cup butter, softened
• 2-1/2 cups confectioners' sugar
• 2 teaspoons clear vanilla extract
• TOPPINGS:
• White baking chips, melted
• Finely chopped pecans