Preheat your oven to 350°F (175°C) and line a cupcake tin with paper liners.
In a large bowl, whisk together the flour, sugar, cocoa powder, baking powder, baking soda, and salt.
Add the milk, vegetable oil, and vanilla extract to the dry ingredients and mix until well combined.
Carefully add the boiling water to the batter and mix until smooth. The batter will be thin.
Pour the batter into the cupcake liners, filling each about two-thirds full.
Bake for 18-20 minutes, or until a toothpick inserted into the center comes out clean. Let cool completely.
To make the ganache, heat the heavy cream in a small saucepan until it just begins to simmer. Remove from heat and pour over the chopped chocolate. Let sit for 2-3 minutes, then stir until smooth.
Once the cupcakes are cool, dip the tops into the ganache or spread it on with a knife. Let the ganache set before serving.