Chocolate Whoopie Pies with Vanilla Cream Cheese Fluff

Ingredients

• 1/2 teaspoon pure vanilla extract
• 2 cups confectioners’ sugar
• 1 tablespoon pure vanilla extract
• 2 sticks unsalted butter, softened
• 2 1/4 cups all-purpose flour
• 2 large eggs
• 1/4 teaspoon cream of tartar
• 1/2 teaspoon kosher salt
• 1 1/4 cups sugar
• 1 1/2 teaspoons baking soda
• 1/4 cup plus 2 tablespoons unsweetened cocoa powder
• 1 pound cream cheese, at room temperature
• Generous pinch of kosher salt
• 1 1/2 sticks unsalted butter, softened
• Crushed candy canes, for rolling
• 1 cup whole milk