Preheat the oven to 350°F and generously grease a 9-inch round cake pan or a 9 x 9-inch or 8 x 8-inch square pan.
In a large bowl, whisk together the flour, cocoa powder, baking powder, espresso powder, and salt. Then, whisk in the milk, oil, eggs, and vanilla extract.
Transfer the batter to the prepared pan and bake for 25 to 35 minutes, or until a toothpick inserted into the center comes out clean. Let the cake cool in the pan for 5 minutes before transferring it to a wire rack to cool.
Ganache
Place chopped chocolate in a medium, heat-proof bowl and set aside.
Heat the cream until it begins to simmer. Pour the hot cream over the chopped chocolate and stir until smooth.
Let cool until it thickens; about 30 to 40 minutes. Before serving, spread onto cooled cake and enjoy!
Notes
To freeze: Wrap the cooled cake with plastic wrap followed by a layer of foil. Store in a freezer bag for up to 2 months. To serve, thaw in the refrigerator overnight in its wrapping.