Preheat oven to 350 and line a muffin tin with 12 cupcake liners.
In a large bowl, whisk together the sugar, flour, cocoa, baking powder, baking soda and salt.
In a large measuring cup, combine the milk, vegetable oil, vanilla, and 1 egg.
Using a mixer, slowly add the wet ingredients to the dry and mix until combined.
Bring the 1/2 cup water to boil and add the espresso to it. Immediately add this to the batter and mix until combined. It will be thin and watery.
Fill each cupcake liner with about 1/4 cup of batter.
Bake about 18 minutes, until toothpick stuck in the center is mostly clean. Let cool in tin for 5 minutes, then remove and cool completely on a rack.
When your cupcakes are cooled, get started on the 7-minute frosting. Recipe I used is up above in instructions, but any basic 7-minute frosting would be fine.
If your cupcakes have a dome, use a serrated knife to shave a bit of the top off and level them. Now core out each cupcake for the filling. I just use a small metal veggie peeler and carve out of a little rough circle shape from the center of the cupcake. Fill with frosting.
Place your chocolate in a small bowl and set aside.
Bring your heavy cream just barely to a simmer and take off the heat.
Pour heavy cream over chocolate and cover the small bowl with a lid. Set aside for 3 minutes to soften the chocolate.
Using a whisk, gently mix the cream and chocolate together in one direction, not vigorously. It will eventually come together in a smooth, glossy, beautiful ganache.
Let cool for a few minutes until firmed up just a bit for spreading over cupcakes. I used an offset spatula to spread it just to the edges; dunking the whole cupcake upside down in the ganache resulted in a mess, so I would avoid that way with this recipe 🙂
Put the ganache-covered cupcakes in the fridge for 10 minutes to firm up the ganache. Make the swirl on top using the leftover white frosting.