Preheat the oven to 350 F; line a cupcake pan with 12 liners, set aside

In a large bowl, whisk together the flour, sugar, cocoa powder, espresso powder, baking powder, and baking soda.

In a separate bowl, whisk together the buttermilk, oil, eggs and vanilla extract. Pour the wet ingredients into the dry ingredients and stir until just combined.

Divide the batter evenly between the 12 cupcake liners, then bake in the preheated oven for 16-18 minutes, or until a toothpick inserted in the center comes out clean.

Prepare the frosting by adding the granulated sugar, corn syrup and water to a medium saucepan over medium heat. Bring to a boil, whisking occasionally, and then allow to simmer until the mixture reaches 240F.

Meanwhile, beat the egg whites until frothy, then add the cream of tartar and whip until soft peaks form.

With the mixer running on medium speed, carefully pour the boiling sugar mixture into the egg whites in a slow steady stream down the side of the bowl.

Whip on high until the mixture is thick, smooth and very white.

Once the cupcakes have cooled, pipe a generous layer of frosting on top. Place in the fridge to chill at least 30 minutes

Melt the chocolate in 30 second intervals using the microwave, then stir in the coconut oil until chocolate is thinned. Dip each cupcake frosting side down into the chocolate mixture, allowing excess to drip off.