Preheat your oven to 350°F (175°C).
Lightly grease an 8-inch or 9-inch round cake pan with non-stick spray and line the base with parchment paper.
In a large bowl, whisk together the flour, sugar, cocoa powder, baking powder, and salt until evenly combined.
Add the oil, egg, vanilla, and milk into the dry ingredients and beat for about 30 seconds until smooth.
Carefully pour in the boiling water mixed with coffee and stir until the batter looks glossy and thin.
Pour the batter into the prepared cake pan and bake for 40–45 minutes, or until a toothpick inserted in the center comes out with moist crumbs (not wet batter).
Remove the cake from the oven and allow it to cool in the pan for 20 minutes before transferring it to a wire rack to cool completely.
For the ganache, gently heat the cream in a small saucepan over low heat without letting it simmer or boil.
Turn off the heat, add the chocolate chips, cover the pan, and let sit for 5 minutes.
Stir slowly with a spatula or spoon until the ganache is smooth and glossy, then refrigerate for 1 to 1½ hours until thick.
Spread before frosting the cooled cake.