Chocolate Birthday Cupcakes with Vanilla Frosting

Ingredients

• 1/2 cup plus 2 tablespoons milk
• 1 teaspoon white vinegar
• 1/2 cup cocoa powder
• 1/2 cup hot water
• 1 cup granulated sugar
• 1/2 cup shortening
• 4 teaspoons plus 2 teaspoons vanilla extract
• 2 eggs
• 1 1/2 cups all purpose flour
• 1 teaspoon baking soda
• 8 cups confectioner's sugar
• 2 sticks unsalted butter
• food coloring optional
• sprinkles optional