Preheat the oven to 350°F. Line a muffin pan with paper liners and set aside.
In a bowl combine the flour, cocoa powder, baking soda and salt. Stir together and set aside.
In another bowl, combine the sugar and butter and beat on medium-high speed until light and fluffy. Mix in the egg until incorporated.
In another bowl, combine the buttermilk, Coke, maraschino cherry juice, and vanilla extract and stir to combine.
Mix the dry ingredients into the butter-sugar mixture on low speed, alternately with the liquid ingredients, beginning and ending with the dry ingredients and mixing just until incorporated. Divide the batter evenly between the cupcake liners.
Insert 1 maraschino cherry in the middle of each cupcake and cover with batter.
Bake for about 22 minutes, or until a toothpick inserted in the center comes out clean. Allow to cool in the pan 5 minutes, then transfer to a wire rack to cool completely.
To make the glaze, combine the icing sugar and Coke in a small bowl and whisk until smooth. Spoon or drizzle a small amount of the top of each cupcake and allow to set.
To make the whipped cream topping, add the heavy cream to the bowl of a stand mixer fitted with the whisk attachment. Begin whipping on medium speed, slowly adding the icing sugar and gradually increasing the speed to high as the cream holds soft peaks. Whip until the cream holds stiff peaks. Spoon the whipped cream on top of the cupcakes and top each with a maraschino cherry.